The drought is much discussed in the media every day now and from my own research (drawing graphs of sea temperature related to land temperature) I have observed that very often when sea temperatures are higher than land temperatures rain occurs. This agrees with theory that says most evaporation into the air from the sea occurs when the sea is warmer than air. This is because if the air is warmer than the sea the sea cools the air above it and the relative humidity of the air becomes higher. Because less evaporation occurs into air with higher relative humidity the air will not take up so much moisture by evaporation. Why does the relative humidity of air become higher when it cools? Well imagine you are in a house and you warm the air in the house. The air expands and some of it goes out via windows, etc. Now imagine the warming of the air inside the house occurs rapidly and the air does not have time to mix with the colder air when it goes out windows, etc. Then the components of the warm air are the same and the mass of each of the components (water vapour, nitrogen, etc) is the same. This means that the mole ratio of each of the components is the same in your heated air as it was before heating. Now the pressure inside the house quickly becomes the same as the pressure outside or air would rush in or rush out. The pressure (partial pressure) of each component such as water vapour is the total pressure (which remains the same) times the mole ratio of that component (which remains the same). The partial pressure of water vapour is therefore the total pressure (which remains the same) times the mole ratio of the water vapour (which remains the same).
So the vapour pressure in the heated air inside the house is the same as the vapour pressure of the vapour before heating. Now relative humidity is the ratio of vapour pressure to the vapour pressure there would be if the air was saturated with water vapour. The latter can be found using saturation vapour tables. The latter changes (increases) with rising temperature so the ratio (vapour pressur)/(saturation vapour pressure at that temperature) decreases with rising temperature. Saying it again, looking at weather reports you will see that relative humidity usually decreases as temperature rises (unless moisture comes in), because the saturation vapour pressure increases as temperature rises, ie constant vapour pressure/increased saturation vapour pressure is a smaller ratio.
My solution is to use spray pumps over the sea (operated by wave motion) to increase evaporation over the sea and to use solar air heaters on all rooftops to get the air to rise when it comes off the sea. This will cause convectional rain. To build your own solar air heater see http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm
Note that the temperature of the Arabian Gulf waters can be well over 30 deg C, but there is little rain. In the Arabian Gulf the temperature of the water is low relative to land air temperatures during the day.
Tuesday, May 23, 2017
Friday, May 19, 2017
Trees can increase air pollution - use air convection
http://newatlas.com/trees-increase-smog-ozone-heat-wave/49607/?utm_source=Gizmag+Subscribers&utm_campaign=090be4bd72-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-090be4bd72-92792417
says:
"A recent study by a Berlin-based team of scientists has revealed that during heat waves, trees in a city can actually contribute to higher levels of air pollution." When plants are hot they can release more volatile organic compounds and this reacts with nitrogen oxides to form ozone. Ozone is a major pollution hazard. One can reduce nitrogen oxides by having electric cars. See later in this blog for converting ammonia to hydrogen for fuel cells for electric cars. Again solar air heaters can increase convection of air and dilute pollution. On how to build your own solar air heater, see http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm
says:
"A recent study by a Berlin-based team of scientists has revealed that during heat waves, trees in a city can actually contribute to higher levels of air pollution." When plants are hot they can release more volatile organic compounds and this reacts with nitrogen oxides to form ozone. Ozone is a major pollution hazard. One can reduce nitrogen oxides by having electric cars. See later in this blog for converting ammonia to hydrogen for fuel cells for electric cars. Again solar air heaters can increase convection of air and dilute pollution. On how to build your own solar air heater, see http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm
Tuesday, May 16, 2017
Energy and water filtration
I heard about CSIRO's research re getting hydrogen from ammonia - see http://newatlas.com/
Of course using natural gas to make the ammonia gives a lot of carbon dioxide. But could the carbon dioxide be used to filter massive amounts of water as in http://newatlas.com/
Of course using natural gas to make the ammonia gives a lot of carbon dioxide. But could the carbon dioxide be used to filter massive amounts of water as in http://newatlas.com/
Sunday, April 23, 2017
Hot roof to reduce global warming
Well I have been advocating growing trees in deserts to take carbon dioxide out of the air. But to grow trees you need rain. My personal device to create rain will be illustrated, but first let me point out that research shows that cool roofs are reducing rainfall — see https://www.scientificamerican.com/article/cool-roofs-may-have-side-effects-on-regional-rainfall/ My personal device is a sort of hot roof. It consists of a black sheet of plastic to absorb solar energy and another sheet of plastic with a shiny surface. The black sheet is placed a few centimetres above the sheet of plastic with a shiny metal surface that reflects heat back to the black sheet -see http://www.houstoncoolmetalroofs.com/cool-roof-information/cool-roof-design-texas/ to see how it works. This two sheet plastic device is made so it can easily be fitted to roofs. It will be very cheap to make. Air will heat up between the two plastic sheets and rise by natural convection, increasing convectional rain. The clouds formed will cool Earth. If this is two-sheet device is placed on the sand in deserts and on every rooftop more rain will result and trees can be grown in deserts and other places. Here is some more evidence that colour of land affects rainfall: https://eos.org/articles/more-intense-rains-in-u-s-midwest-tied-to-farm-mechanization?utm_source=Eos%20Primary%20List&utm_medium=email&utm_content=more-intense-rains-in-u-s-midwest-tied-to-farm-mechanization&utm_campaign=5022c1d8f8-Weekly_All_Content_Digest&utm_term=0_f923f18da4-5022c1d8f8-522497757
Tuesday, April 18, 2017
Rain to the desert using hot rocks at night
The desert air is very hot and has a low relative humidity. But the desert air holds a lot of moisture because hot air does hold a lot of moisture even if the relative humidity is fairly low. When desert air cools down the relative humidity increases and at night is often high. At night, if we could cause rain, the rain would not evaporate as it is falling, because the air is cool and relative humidity is high.
Here is my idea for rain in deserts: With rocky areas, paint the rocks black (or so that they are dark). If there are no rocks then build concrete or brick structures and paint them black so that they heat up during the day. Stone, brick and concrete have high volumetric heat capacities (a small volume can hold a lot of heat). At night the hot stone, brick or concrete will heat up air that has a high relative humidity. The air will rise and convectional rain will occur. The area painted black will have to be large, but a massive amount of air can be heated from a relatively small volume of rock. In fact rock has a heat capacity of about 0.8 kJ per kilogram per 1 deg C temperature increase. One cubic metre of rock weighs very roughly 2700 kg, so a cubic metre of rock has can store of 2700x0.8=2160 kJ per cubic metre if its temperature is raised 1 deg C. One cubic metre of air can store about 1.2 kJ of energy if it is raised 1 deg C.
Air: 1.2 kJ per cubic metre per deg C
Stone: 2160 kJ per cubic metre per deg C (very roughly).
A variation could be to reflect sun, using mirrors, onto ordinary rocks, or rocks painted black, so the rocks heat up more.
Desert air can get very cold at night.
EXAMPLE: The desert air has temperature 40 deg C and at this temperature the relative humidity (RH) is 10%.
Night approaches and the temperature falls. As it falls RH increases
T RH
35 13.1%
30 17.4%
25 23.3%
20 31.6%
15 43.3%
10 60.1%
5 84.6%
2.6 100%
Here is my idea for rain in deserts: With rocky areas, paint the rocks black (or so that they are dark). If there are no rocks then build concrete or brick structures and paint them black so that they heat up during the day. Stone, brick and concrete have high volumetric heat capacities (a small volume can hold a lot of heat). At night the hot stone, brick or concrete will heat up air that has a high relative humidity. The air will rise and convectional rain will occur. The area painted black will have to be large, but a massive amount of air can be heated from a relatively small volume of rock. In fact rock has a heat capacity of about 0.8 kJ per kilogram per 1 deg C temperature increase. One cubic metre of rock weighs very roughly 2700 kg, so a cubic metre of rock has can store of 2700x0.8=2160 kJ per cubic metre if its temperature is raised 1 deg C. One cubic metre of air can store about 1.2 kJ of energy if it is raised 1 deg C.
Air: 1.2 kJ per cubic metre per deg C
Stone: 2160 kJ per cubic metre per deg C (very roughly).
A variation could be to reflect sun, using mirrors, onto ordinary rocks, or rocks painted black, so the rocks heat up more.
Desert air can get very cold at night.
EXAMPLE: The desert air has temperature 40 deg C and at this temperature the relative humidity (RH) is 10%.
Night approaches and the temperature falls. As it falls RH increases
T RH
35 13.1%
30 17.4%
25 23.3%
20 31.6%
15 43.3%
10 60.1%
5 84.6%
2.6 100%
Wednesday, March 15, 2017
Rain when sea temperatures are higher than air temperatures over land?
Some time ago I made and showed graphs indicating there was often rain when sea temperatures were higher than land air temperatures. Yesterday I came across this graph in a physical geography book showing more rain when sea temperatures were higher. I do not know if the author noticed this as well - cannot see where he/she mentions it. See https://books.google.co.za/books?id=iU-pGIOqS1AC&pg=PA38&lpg=PA38&dq=air+and+sea+temperatures+and+rainfall+Canton+Island+Boucher+1975&source=bl&ots=dMMHHLbX5g&sig=rCPunkj6nZuo044iNSUGgIaSdJs&hl=en&sa=X&ved=0ahUKEwiatdO5nNjSAhWsJcAKHS9dC1QQ6AEIGjAA#v=onepage&q=air%20and%20sea%20temperatures%20and%20rainfall%20Canton%20Island%20Boucher%201975&f=false
Something that will give credibility to my idea is the graph below. For my calculations I have used the following conditions:
1) Temperature of air over the land is 26 deg C.
2) There is a 2 m/s wind over the sea.
3) The relative humidity of the land air is 50% and pressure = 100 kPa.
4) The air blows from the land to the sea and at the sea surface where evaporation occurs, the air cools or warms to the temperature of the sea temperature.
5) The variable is the sea temperature.
1) Temperature of air over the land is 26 deg C.
2) There is a 2 m/s wind over the sea.
3) The relative humidity of the land air is 50% and pressure = 100 kPa.
4) The air blows from the land to the sea and at the sea surface where evaporation occurs, the air cools or warms to the temperature of the sea temperature.
5) The variable is the sea temperature.
a) When Tsea=14 deg C the air becomes saturated and condensation occurs (I have used a 100% RH for this on the graph), the evaporation rate from the sea surface is 0 microns of water per hour.
b) When Tsea=16 deg C, the RH of the air over the sea surface is 92.5% (RH increases when T decreases), the evaporation rate is 55 microns per hour.
I have put the RH and the evaporation rate in microns on the same vertical axis (not really correct, but convenient). So Tsea runs from 14 deg C to 34 deg C, the RH runs from 100% to 31.6% (see graph), the evaporation rate runs from 0 (at 14 deg C) to 1532 microns of water per hour (if the water were in a basin, water levels would drop from 0 microns per hour when T=14 deg C, to 1532 microns per hour when T=36 degC). As one can see, when sea temperatures are high relative to land temperatures, more evaporation occurs. I used an equation similar to the "Evaporation from a water surface" equation by Engineering toolbox to calculate evaporation rates (they depend on relative humidity and temperature and wind speed).
b) When Tsea=16 deg C, the RH of the air over the sea surface is 92.5% (RH increases when T decreases), the evaporation rate is 55 microns per hour.
I have put the RH and the evaporation rate in microns on the same vertical axis (not really correct, but convenient). So Tsea runs from 14 deg C to 34 deg C, the RH runs from 100% to 31.6% (see graph), the evaporation rate runs from 0 (at 14 deg C) to 1532 microns of water per hour (if the water were in a basin, water levels would drop from 0 microns per hour when T=14 deg C, to 1532 microns per hour when T=36 degC). As one can see, when sea temperatures are high relative to land temperatures, more evaporation occurs. I used an equation similar to the "Evaporation from a water surface" equation by Engineering toolbox to calculate evaporation rates (they depend on relative humidity and temperature and wind speed).
Tuesday, March 14, 2017
Water source heat pumps for rain.
Water source heat pumps with large moving bodies of water are very efficient – even more so than air and ground source heat pumps.
Idea: 1) Build a huge tank or tanks of air above the sea on steel frames. 2) Use water source heat pumps and solar energy to warm the air in the tanks. 3) Spray water into the tanks to evaporate in the warm air.
http://www.thegreenage.co.uk/tech/water-source-heat-pumps/ describes these heat pumps..
If a big tank of air is situated in the region near a desert and this air is heated using a water source heat pump and solar energy that is reflected by mirrors onto the tank, seawater can be sprayed into the warm air and evaporated by the hot air. The moisture levels and heat levels of the air could be controlled and the air can be manufactured and released when there is a sea breeze (breeze onto land). The warm moist air will rise by convection to form rain.
The heat exchange of the water source heat pump could take place in the warm Arabian Gulf waters, or in the warm Red sea, making the system very efficient.
With regard to the mirrors focusing solar energy onto the tank with air in, a square kilometre of land or sea surface can often provide about 5 000 000 kWh of energy in a day (5 kWh per square metre per day ). This energy could be focused by the mirrors onto the tank described, or onto a number of tanks. Now 1 kWh can evaporate about 1.6 litres (1.6 kg) of water, so this is enough to evaporate about 5 000 000x1.6 = 8 000 000 litres ( 8000 metric tons) of water. This extra 8000 tons of vapour will increase humidity in the general surroundings and moist air could be targeted to various ares to some extent, by controlling temperature (different rate of rising with different temperatures) and calculating sea breeze direction and velocities. At a relative humidity of 40% and a temperature of 30 deg C 1 cubic kilometre of air holds 12140 metric tons of water vapour. At the same temperature and an RH of 66% this cubic kilometre holds 20032 metric tons (about 8000 tonnes more).
Idea: 1) Build a huge tank or tanks of air above the sea on steel frames. 2) Use water source heat pumps and solar energy to warm the air in the tanks. 3) Spray water into the tanks to evaporate in the warm air.
http://www.thegreenage.co.uk/tech/water-source-heat-pumps/ describes these heat pumps..
If a big tank of air is situated in the region near a desert and this air is heated using a water source heat pump and solar energy that is reflected by mirrors onto the tank, seawater can be sprayed into the warm air and evaporated by the hot air. The moisture levels and heat levels of the air could be controlled and the air can be manufactured and released when there is a sea breeze (breeze onto land). The warm moist air will rise by convection to form rain.
The heat exchange of the water source heat pump could take place in the warm Arabian Gulf waters, or in the warm Red sea, making the system very efficient.
With regard to the mirrors focusing solar energy onto the tank with air in, a square kilometre of land or sea surface can often provide about 5 000 000 kWh of energy in a day (5 kWh per square metre per day ). This energy could be focused by the mirrors onto the tank described, or onto a number of tanks. Now 1 kWh can evaporate about 1.6 litres (1.6 kg) of water, so this is enough to evaporate about 5 000 000x1.6 = 8 000 000 litres ( 8000 metric tons) of water. This extra 8000 tons of vapour will increase humidity in the general surroundings and moist air could be targeted to various ares to some extent, by controlling temperature (different rate of rising with different temperatures) and calculating sea breeze direction and velocities. At a relative humidity of 40% and a temperature of 30 deg C 1 cubic kilometre of air holds 12140 metric tons of water vapour. At the same temperature and an RH of 66% this cubic kilometre holds 20032 metric tons (about 8000 tonnes more).
Monday, March 13, 2017
Artificial heated lagoons for rain
With colder sea temperatures than land temperatures (eg Western Cape in summer, UAE, etc), cold air from the sea does not hold a lot of moisture and when it blows onto land and heats up, relative humidity decreases. Also this cold air does not easily rise by convection to form rain. One of my ideas is artificial lagoons with solar energy reflected into them to heat the water.
With deep ocean one has a limitless supply of heat from the water (evaporation cools the surface, but there is plenty of heat from the water to heat it up again), but the surface can only be heated to about the sea temperatures below the surface. About 43% of energy from the sun is of visible light frequency. Visible light has the distinct property of being able to penetrate seawater to some depth, whereas the infrared generally gets absorbed quickly. So if you have shallow pools with dark bottoms you suddenly have 43% of the solar energy available in a shallow pool that normally would have heated a huge body of water a little, but there is very little energy that can be used from the water to heat the surface when it cools from evaporation. As I am looking for high temperatures I have to think about shallow pools rather than deep sea. With a shallow pool the energy comes mainly from the solar energy (not the water). If one wants high temperatures (with evaporation and radiation the shallow pool can cool quickly), one needs ways of getting solar energy to the pool or lagoon, etc. So my proposal has been shallow lagoons made by bulldozing out of the sand and with mirrors to reflect solar energy into the lagoon. Say the sun provides 700 W of energy per square metre of water surface. Eventually the temperature of the lagoon water gets so high (at about 26.5 deg C) that all the 700 W per sqare metre is needed for evaporation and so mirrors will be needed for more energy. My graph below shows the 700 W straight line (0.7 kW), the evaporation rate on a 1 sq metre surface (upper curve kg/hour) and the power needed for the evaporation (lower curve kW). Not correct to have kW and kg/hour on the vertical axis, but it works out. The conditions are a 40% relative humidity, a 3 m/s wind over the surface and an atmospheric pressure of 100 kPa.
With deep ocean one has a limitless supply of heat from the water (evaporation cools the surface, but there is plenty of heat from the water to heat it up again), but the surface can only be heated to about the sea temperatures below the surface. About 43% of energy from the sun is of visible light frequency. Visible light has the distinct property of being able to penetrate seawater to some depth, whereas the infrared generally gets absorbed quickly. So if you have shallow pools with dark bottoms you suddenly have 43% of the solar energy available in a shallow pool that normally would have heated a huge body of water a little, but there is very little energy that can be used from the water to heat the surface when it cools from evaporation. As I am looking for high temperatures I have to think about shallow pools rather than deep sea. With a shallow pool the energy comes mainly from the solar energy (not the water). If one wants high temperatures (with evaporation and radiation the shallow pool can cool quickly), one needs ways of getting solar energy to the pool or lagoon, etc. So my proposal has been shallow lagoons made by bulldozing out of the sand and with mirrors to reflect solar energy into the lagoon. Say the sun provides 700 W of energy per square metre of water surface. Eventually the temperature of the lagoon water gets so high (at about 26.5 deg C) that all the 700 W per sqare metre is needed for evaporation and so mirrors will be needed for more energy. My graph below shows the 700 W straight line (0.7 kW), the evaporation rate on a 1 sq metre surface (upper curve kg/hour) and the power needed for the evaporation (lower curve kW). Not correct to have kW and kg/hour on the vertical axis, but it works out. The conditions are a 40% relative humidity, a 3 m/s wind over the surface and an atmospheric pressure of 100 kPa.
Friday, March 3, 2017
Growing trees in the deserts
https://www.adn.com/arctic/2017/02/27/scientists-just-measured-a-rapid-growth-in-acidity-in-the-arctic-ocean/
refers to acidification of the Arctic Ocean as well as global warming and ice. It seems to me that a way to take massive amounts of carbon dioxide out of the atmosphere is to grow trees in deserts. First, more rain would have to occur in deserts. One problem with global warming is that the land heats up faster than the oceans. Imagine hotter air flowing from land to cooler ocean. The hot air cools down where air meets water and the relative humidity of this cooling air rises and the air can become saturated immediately above the ocean where evaporation could have taken place. Because no net evaporation can occur into saturated air there is a problem with the land and sea breeze mechanism - no moisture is being picked up by the air. An answer would be to provide hot moist surfaces over the ocean so that the air from land is warmed rather than cooled when flowing over the sea, Warm air can hold more moisture, so evaporation will occur. Now when the air flows back onto land (sea breeze, etc) it will have more moisture than before and rain can result. Clouds absorb thermal infrared and so I presume sea spray will also. So if one puts black objects (that heat up in the sun) in the sea spray, the spray will absorb the thermal infrared radiation from the hot objects and will evaporate. Sea spray will also evaporate by having contact with hot these objects. Black netting hung in the spray should do the trick, because this netting will get hot and radiate thermal infrared. Sunlight itself has almost no thermal infrared in, but does radiate infrared of a higher frequency. My Planck's formula integration tells me that about 0.51% (less than 1%) of solar radiation is thermal infrared (5 to 20 microns in wavelength) radiation. On the other hand a blackbody (something like black netting approximates this) having a temperature of 40 deg C has about 74.2% of its radiated energy in the 5 to 20 micron range. This black netting in the ocean method could be used with deserts that are near cold seas, but have a lot of sunshine. Resulting rain could then get trees growing in deserts to absorb massive amounts of carbon dioxide. Desert soil is often very fertile. Black cement rocks in the sea to create spray from waves and absorb solar energy to heat spray could also be used along with black netting. Another way to make the seawater hotter is to have shallow pools of seawater (preferably with dark bottoms) because shallow pools get hotter in sunny weather.
It seems that the following could occur:
1) From morning until about midday the air over the sea will become humid because of shallow pools and spray heated on dark objects.
2) At about midday the sea breeze will start (air will blow onto land from the sea). This will bring moist air to the land.
3) At night the air will blow from land to sea, but the air will become more moist than usual over the sea because of the spray.
4) The process of steps 1, 2 and 3 will repeat itself - at about midday moist air will start moving onto the land, etc.
Spray could also be generated by a spray pump using wave motion to drive it.
To get air to rise over the land when it blows from sea to land, use solar air heaters on roofs of the city and elsewhere. Solar air heaters can heat massive volumes of air. The solar air heaters will shade roofs and keep them cool, but will heat air and get it to rise. Another way of getting air to rise over an area is to make that area dark with biochar. The dark land will heat up more relative to lighter coloured land and heat air. When clouds form they will have a cooling effect on the Earth.
refers to acidification of the Arctic Ocean as well as global warming and ice. It seems to me that a way to take massive amounts of carbon dioxide out of the atmosphere is to grow trees in deserts. First, more rain would have to occur in deserts. One problem with global warming is that the land heats up faster than the oceans. Imagine hotter air flowing from land to cooler ocean. The hot air cools down where air meets water and the relative humidity of this cooling air rises and the air can become saturated immediately above the ocean where evaporation could have taken place. Because no net evaporation can occur into saturated air there is a problem with the land and sea breeze mechanism - no moisture is being picked up by the air. An answer would be to provide hot moist surfaces over the ocean so that the air from land is warmed rather than cooled when flowing over the sea, Warm air can hold more moisture, so evaporation will occur. Now when the air flows back onto land (sea breeze, etc) it will have more moisture than before and rain can result. Clouds absorb thermal infrared and so I presume sea spray will also. So if one puts black objects (that heat up in the sun) in the sea spray, the spray will absorb the thermal infrared radiation from the hot objects and will evaporate. Sea spray will also evaporate by having contact with hot these objects. Black netting hung in the spray should do the trick, because this netting will get hot and radiate thermal infrared. Sunlight itself has almost no thermal infrared in, but does radiate infrared of a higher frequency. My Planck's formula integration tells me that about 0.51% (less than 1%) of solar radiation is thermal infrared (5 to 20 microns in wavelength) radiation. On the other hand a blackbody (something like black netting approximates this) having a temperature of 40 deg C has about 74.2% of its radiated energy in the 5 to 20 micron range. This black netting in the ocean method could be used with deserts that are near cold seas, but have a lot of sunshine. Resulting rain could then get trees growing in deserts to absorb massive amounts of carbon dioxide. Desert soil is often very fertile. Black cement rocks in the sea to create spray from waves and absorb solar energy to heat spray could also be used along with black netting. Another way to make the seawater hotter is to have shallow pools of seawater (preferably with dark bottoms) because shallow pools get hotter in sunny weather.
It seems that the following could occur:
1) From morning until about midday the air over the sea will become humid because of shallow pools and spray heated on dark objects.
2) At about midday the sea breeze will start (air will blow onto land from the sea). This will bring moist air to the land.
3) At night the air will blow from land to sea, but the air will become more moist than usual over the sea because of the spray.
4) The process of steps 1, 2 and 3 will repeat itself - at about midday moist air will start moving onto the land, etc.
Spray could also be generated by a spray pump using wave motion to drive it.
To get air to rise over the land when it blows from sea to land, use solar air heaters on roofs of the city and elsewhere. Solar air heaters can heat massive volumes of air. The solar air heaters will shade roofs and keep them cool, but will heat air and get it to rise. Another way of getting air to rise over an area is to make that area dark with biochar. The dark land will heat up more relative to lighter coloured land and heat air. When clouds form they will have a cooling effect on the Earth.
Could biochar be used to clear fog?
Could biochar be used to clear fog? After the biochar dust has fallen to the ground the ground should be more fertile.
Fog: Shipping and aviation is sometimes delayed by fog. Fog will reflect some sunlight and absorb some infrared. If you distributed fine biochar particles in the fog these would absorb most of the solar energy (light and infrared) and the fog should heat up and disperse. The Japanese use biochar on snow to help melt snow. The biochar decreases the albedo of the snow and so it absorbs solar energy and melts days sooner.
Calculations: Wikipedia says that in fog there is typically 50 000 kg of water per cubic kilometre of fog (liquid water content of fog is typically 0.05 g per cubic metre). 2257 kJ is needed to vaporise 1 kg of water.
To vaporize this 50 000 kg of water takes about 50 000x2257 kJ=112 850 000 kJ = 112 850 000/3600 kWh = 31347 kWh.
Say the fog is 100 m deep. Then an area of 10 square kilometres has a cubic kilometre of fog. Say the solar energy falling per square metre of ground is 2 kWh per day. Then 2x10x1000000 kWh = 20000000 kWh falls on the 10 square kilometres. This is far more than the 31347 kWh needed to vaporize the fog. Of course not all the solar energy will be absorbed by the fog with biochar dust in and some solar energy must go into heating air as well, but there is a lot of solar energy to spare (31347 kWh needed for vaporization and 20 000 000 kWh available from the sun).
Fog: Shipping and aviation is sometimes delayed by fog. Fog will reflect some sunlight and absorb some infrared. If you distributed fine biochar particles in the fog these would absorb most of the solar energy (light and infrared) and the fog should heat up and disperse. The Japanese use biochar on snow to help melt snow. The biochar decreases the albedo of the snow and so it absorbs solar energy and melts days sooner.
Calculations: Wikipedia says that in fog there is typically 50 000 kg of water per cubic kilometre of fog (liquid water content of fog is typically 0.05 g per cubic metre). 2257 kJ is needed to vaporise 1 kg of water.
To vaporize this 50 000 kg of water takes about 50 000x2257 kJ=112 850 000 kJ = 112 850 000/3600 kWh = 31347 kWh.
Say the fog is 100 m deep. Then an area of 10 square kilometres has a cubic kilometre of fog. Say the solar energy falling per square metre of ground is 2 kWh per day. Then 2x10x1000000 kWh = 20000000 kWh falls on the 10 square kilometres. This is far more than the 31347 kWh needed to vaporize the fog. Of course not all the solar energy will be absorbed by the fog with biochar dust in and some solar energy must go into heating air as well, but there is a lot of solar energy to spare (31347 kWh needed for vaporization and 20 000 000 kWh available from the sun).
Thursday, February 23, 2017
Are cool roofs reducing rainfall and increasing pollution?
Are cool roof paints reducing rainfall?
Regarding pollution, http://iopscience.iop.org/article/10.1088/1748-9326/11/6/064004/meta says,
"The lowered wind speeds and vertical mixing during daytime led to stagnation of air near the surface, potentially causing air quality issues."
Why not distribute a solar air heater that can be attached to roofs? The solar air heaters will shade roofs during the day and heat air, but also be cooled by the air passing through. This should cause cloud formation which will keep the city warm at night. Paint manufacturers could team up with solar air heater manufacturers to produce this air heating, roof cooling and rain enhancing solar air heater on roofs situation.
See http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm for information on solar air heaters.
Drought in coastal cities: I am wondering if it would not be better to make buildings in, say, Los Angeles a dark colour to heat up more and enhance chances of rain (or use solar air heaters on roofs as mentioned above). One hears about a 10% increase in rainfall due to urban heat island effect. I have done some calculations:
Assume the air from the sea has a relative humidity (RH) of 70% and is at 18 deg C and it blows onto land and heats up over the city, but remains at 18 deg C over the rest of the area (a simplification to make calculations easier). My calculations use an environmental lapse rate of 6.5 deg C per km rise and a dry adiabatic lapse rate of 9.8 deg C per km rise. The dew point of the sea and land air remains at 12.5 deg C whether heated or not, but the RH changes on the air being heated. My calculations show the number of degrees the air heats up over the city (1 deg means it heats up to 19 deg C from the 18 deg sea air temperature). Then they show the change in RH of the air after heating. Then they show the height to which the heated air can rise and the height to which it needs to rise for clouds to form: 0) Heats up 0 deg over city, RH remains 70%, the air can rise 0 m and it needs to rise 694 m for clouds to form. 1) Heats up 1 deg over city, RH is now 65.8%, the air can rise 303 m and it needs to rise 819 m for clouds to form 2) Heats up 2 deg over city, RH is now 61.8%, the air can rise 606 m and it needs to rise 944 m for clouds to form 3) Air heats up 3 deg over city RH is now 58.1%, the air can rise 909 m and it needs to rise 1069 m for clouds to form 4) Air heats up 4 deg over city RH is now 54.6%, the air can rise 1212 m and it needs to rise 1194 m for clouds to form 5) Air heats up 5 deg over city RH is now 51.4%, the air can rise 1515 m and it needs to rise 1319 m for clouds to form 6) Air heats up 6 deg over city RH is now 48.4%, the air can rise 1818 m and it needs to rise 1444 m for clouds to form After step 4 the air is heated enough for clouds to form - see the graph. Note that more cloud formation could cool Earth overall.
Here is another very good design to get air moving upwards:
http://www.houstoncoolmetalroofs.com/cool-roof-information/cool-roof-design-texas/
See https://www.scientificamerican.com/article/cool-roofs-may-have-side-effects-on-regional-rainfall/ which says, "However, they shift rainfall patterns by reducing evapotranspiration, the process by which water evaporates from the ground and enters the atmosphere. In the maximum expansion scenario, cool roofs led to a 4 percent decline in rainfall."
One could increase convection by using solar air heaters made by placing a black piece of corrugated iron roof sheet a few centimetres above a silver sheet of corrugated iron. Another method is to make the soil dark with biochar - plow biochar into the soil. You can make your own biochar by heating wood in a barrel.
You can also paint rocks black: Rocks have a high heat capacity - they hold a lot of heat. If cool roofs reduce rainfall, rocks painted black can increase rainfall.
Just as cool colours can decrease rainfall, so can dark colours incease rainfall by increasing convection. See http://www.xcmag.com/2007/10/thermal-flying-part-2-thermal-generators-and-triggers/
When clouds develop, because of convection, they will help with global warming by cooling the Earth.
Regarding pollution, http://iopscience.iop.org/article/10.1088/1748-9326/11/6/064004/meta says,
"The lowered wind speeds and vertical mixing during daytime led to stagnation of air near the surface, potentially causing air quality issues."
Why not distribute a solar air heater that can be attached to roofs? The solar air heaters will shade roofs during the day and heat air, but also be cooled by the air passing through. This should cause cloud formation which will keep the city warm at night. Paint manufacturers could team up with solar air heater manufacturers to produce this air heating, roof cooling and rain enhancing solar air heater on roofs situation.
See http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm for information on solar air heaters.
Drought in coastal cities: I am wondering if it would not be better to make buildings in, say, Los Angeles a dark colour to heat up more and enhance chances of rain (or use solar air heaters on roofs as mentioned above). One hears about a 10% increase in rainfall due to urban heat island effect. I have done some calculations:
Assume the air from the sea has a relative humidity (RH) of 70% and is at 18 deg C and it blows onto land and heats up over the city, but remains at 18 deg C over the rest of the area (a simplification to make calculations easier). My calculations use an environmental lapse rate of 6.5 deg C per km rise and a dry adiabatic lapse rate of 9.8 deg C per km rise. The dew point of the sea and land air remains at 12.5 deg C whether heated or not, but the RH changes on the air being heated. My calculations show the number of degrees the air heats up over the city (1 deg means it heats up to 19 deg C from the 18 deg sea air temperature). Then they show the change in RH of the air after heating. Then they show the height to which the heated air can rise and the height to which it needs to rise for clouds to form: 0) Heats up 0 deg over city, RH remains 70%, the air can rise 0 m and it needs to rise 694 m for clouds to form. 1) Heats up 1 deg over city, RH is now 65.8%, the air can rise 303 m and it needs to rise 819 m for clouds to form 2) Heats up 2 deg over city, RH is now 61.8%, the air can rise 606 m and it needs to rise 944 m for clouds to form 3) Air heats up 3 deg over city RH is now 58.1%, the air can rise 909 m and it needs to rise 1069 m for clouds to form 4) Air heats up 4 deg over city RH is now 54.6%, the air can rise 1212 m and it needs to rise 1194 m for clouds to form 5) Air heats up 5 deg over city RH is now 51.4%, the air can rise 1515 m and it needs to rise 1319 m for clouds to form 6) Air heats up 6 deg over city RH is now 48.4%, the air can rise 1818 m and it needs to rise 1444 m for clouds to form After step 4 the air is heated enough for clouds to form - see the graph. Note that more cloud formation could cool Earth overall.
Here is another very good design to get air moving upwards:
http://www.houstoncoolmetalroofs.com/cool-roof-information/cool-roof-design-texas/
One could increase convection by using solar air heaters made by placing a black piece of corrugated iron roof sheet a few centimetres above a silver sheet of corrugated iron. Another method is to make the soil dark with biochar - plow biochar into the soil. You can make your own biochar by heating wood in a barrel.
You can also paint rocks black: Rocks have a high heat capacity - they hold a lot of heat. If cool roofs reduce rainfall, rocks painted black can increase rainfall.
Just as cool colours can decrease rainfall, so can dark colours incease rainfall by increasing convection. See http://www.xcmag.com/2007/10/thermal-flying-part-2-thermal-generators-and-triggers/
When clouds develop, because of convection, they will help with global warming by cooling the Earth.
Friday, February 17, 2017
Cool Arctic with heat pipes
Heat pipes are used in the Arctic to keep the ground cold so that structures are secure. The heat pipe, used next to the structure, uses a fluid that is heated in winter by ground temperatures that are higher than the air temperatures. The fluid evaporates, moves up from the ground into the air zone and condenses into liquid, releasing the heat to the cold air. This liquid now moves downwards and the cycle starts again - see thermosyphons section at https://en.wikipedia.org/wiki/Heat_pipe#Permafrost_cooling
Now part of the reason that there is little snowfall in the Arctic is that with thawing and evaporation in summer there is relatively a lot of moisture in the air, but the air is cold (so cannot hold much moisture) and does not rise far enough to cause snow to fall (it needs to be warm so it can rise and cool significantly so that a lot of water vapour condenses out). The thermosyphon warms the air and cools the ground, so there are two benefits. A solar air heater could be used above the thermosyphon so that cool air is drawn in from ground level to cool the top of the thermosyphon. This will dramatically increase the ability of the air to rise far and cause snowfall. Snowfall increases the albedo and so more cooling will occur.
If you put a 1 sq metre solar air heater above the thermosyphon on a clear day at noon on 1 July at the latitude shown on the graph, you can theoretically heat the number of cubic metres of air shown by 1 deg every second. This is for a "facing the sun" solar air heater. A horizontal solar air heater at these latitudes gets much less insolation. There are two important aspects at these latitudes: 1) the amount of air the sun shines through 2) the angle of the solar heater. Both these have been taken into consideration in the calculations.
Now part of the reason that there is little snowfall in the Arctic is that with thawing and evaporation in summer there is relatively a lot of moisture in the air, but the air is cold (so cannot hold much moisture) and does not rise far enough to cause snow to fall (it needs to be warm so it can rise and cool significantly so that a lot of water vapour condenses out). The thermosyphon warms the air and cools the ground, so there are two benefits. A solar air heater could be used above the thermosyphon so that cool air is drawn in from ground level to cool the top of the thermosyphon. This will dramatically increase the ability of the air to rise far and cause snowfall. Snowfall increases the albedo and so more cooling will occur.
If you put a 1 sq metre solar air heater above the thermosyphon on a clear day at noon on 1 July at the latitude shown on the graph, you can theoretically heat the number of cubic metres of air shown by 1 deg every second. This is for a "facing the sun" solar air heater. A horizontal solar air heater at these latitudes gets much less insolation. There are two important aspects at these latitudes: 1) the amount of air the sun shines through 2) the angle of the solar heater. Both these have been taken into consideration in the calculations.
Thursday, February 9, 2017
Clean water from seawater and Arctic clouds
People are worried about heating of Arctic regions. In winter the ice can reflect solar energy and cool Arctic regions, but in summer clouds can reflect solar energy in regions where ice has melted (however increased humidity can increase the greenhouse effect).
One of my "inventions" that could increase the relative humidity (and therefore clouds) is being investigated by a university of technology in South Africa. It could be used for drought areas.
One can dramatically increase relative humidity by adding water to the air.
Calculations for air at 25 deg C: At a 50% relative humidity in a column of air of base of 1 sq metre and height of 1000 m (1000 cubic metre column) there are 11.5 kg of water vapour. In the same column with an RH of 90% there are 20.7 litres of water vapour. If you can add 20.7-11.5 = 9.2 litres you can therefore increase the RH from 50% to 90%. You need 9.2/1.6 = 5.75 kWh to do this (theoretically, since 1 kWh can evaporate 1.6 litres of water). In a day 5.75 kWh of solar energy can fall on the 1 sq metre base of the column in some regions. With higher RH clouds can form more easily.
See also my diagram for clean water from seawater. This apparatus could be used to increase humidity of the surroundings if it was used on every rooftop. Note that the idea is similar to the idea of a solar updraft tower with hot air rising, due to natural convection, through the system. Black mesh or gauze could be put into the greenhouse to give a large moist surface for hot air from the solar air heater to blow over. See https://en.wikipedia.org/wiki/Solar_updraft_tower
http://physicstoday.scitation.org/do/10.1063/PT.5.4018/full/ gives some cloud physics and
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1126&context=natrespapers tells how to spread snow evenly using windbreaks. Snow increases albedo keeping an area cool.
I do not intend to patent my clean water from seawater device, because it is intended to help everybody and I hope people start building it for themselves.
Here is how you can work out relative humidity problems for yourself: You can use the table at http://www.tis-gdv.de/tis_e/misc/klima.htm When relative humidity is 50% and temperature is 25 deg (see table) you find that there are 11.5 g/cubic metre of water vapour (this is the same as 11.5 kg per 1000 cubic metres). Likewise there are 20.7 kg of water vapour per 1000 cubic metres when RH is 90% (see my example above).
http://journals.ametsoc.org/doi/full/10.1175/JCLI3489.1 says
"The effect of a thin snow cover is dramatic, particularly in the NIR. Just 5–10 mm of continuous snow cover raised the broadband albedo from 0.49 to 0.81, nearly as high as values measured for deep snow on the Antarctic Plateau, α = 0.83" and "Wind often cleared the snow from the ice. On one occasion a new snowfall of 2–3 cm raised the albedo from 0.42 to 0.88, and on another occasion a snowfall of 1–2 cm raised the albedo from 0.39 to 0.78."
So my idea is to have windbreaks in the Arctic that spread snow evenly and prevent it from blowing away.
2) Assume emissivity of snow or ice is 0.97.
3) Assume absorptivity of snow or ice changes from 0.6 to 0.2 when snow falls (albedo increases when snow falls and absorptivity decreases).
4) Assume the effective sky temperature is -20 deg C
5) Assume temperature of ice or snow is -5 deg C.
Then for absorptivity of 0.6 (low albedo) the ice/snow has a heat gain of 242 watts per square metre. For an absorptivity of 0.2 (high albedo) the ice/snow absorbs only 42 watts per square metre.
https://nsidc.org/cryosphere/seaice/characteristics/difference.html says, "Because the Arctic Ocean is mostly covered by ice and surrounded by land, precipitation is relatively rare. Snowfall tends to be low, except near the ice edge. Antarctica, however, is entirely surrounded by ocean, so moisture is more readily available. Antarctic sea ice tends to be covered by thicker snow, which may accumulate to the point that the weight of snow pushes the ice below sea level, causing the snow to become flooded by salty ocean waters."
One of my "inventions" that could increase the relative humidity (and therefore clouds) is being investigated by a university of technology in South Africa. It could be used for drought areas.
One can dramatically increase relative humidity by adding water to the air.
Calculations for air at 25 deg C: At a 50% relative humidity in a column of air of base of 1 sq metre and height of 1000 m (1000 cubic metre column) there are 11.5 kg of water vapour. In the same column with an RH of 90% there are 20.7 litres of water vapour. If you can add 20.7-11.5 = 9.2 litres you can therefore increase the RH from 50% to 90%. You need 9.2/1.6 = 5.75 kWh to do this (theoretically, since 1 kWh can evaporate 1.6 litres of water). In a day 5.75 kWh of solar energy can fall on the 1 sq metre base of the column in some regions. With higher RH clouds can form more easily.
See also my diagram for clean water from seawater. This apparatus could be used to increase humidity of the surroundings if it was used on every rooftop. Note that the idea is similar to the idea of a solar updraft tower with hot air rising, due to natural convection, through the system. Black mesh or gauze could be put into the greenhouse to give a large moist surface for hot air from the solar air heater to blow over. See https://en.wikipedia.org/wiki/Solar_updraft_tower
http://physicstoday.scitation.org/do/10.1063/PT.5.4018/full/ gives some cloud physics and
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1126&context=natrespapers tells how to spread snow evenly using windbreaks. Snow increases albedo keeping an area cool.
I do not intend to patent my clean water from seawater device, because it is intended to help everybody and I hope people start building it for themselves.
Here is how you can work out relative humidity problems for yourself: You can use the table at http://www.tis-gdv.de/tis_e/misc/klima.htm When relative humidity is 50% and temperature is 25 deg (see table) you find that there are 11.5 g/cubic metre of water vapour (this is the same as 11.5 kg per 1000 cubic metres). Likewise there are 20.7 kg of water vapour per 1000 cubic metres when RH is 90% (see my example above).
"The effect of a thin snow cover is dramatic, particularly in the NIR. Just 5–10 mm of continuous snow cover raised the broadband albedo from 0.49 to 0.81, nearly as high as values measured for deep snow on the Antarctic Plateau, α = 0.83" and "Wind often cleared the snow from the ice. On one occasion a new snowfall of 2–3 cm raised the albedo from 0.42 to 0.88, and on another occasion a snowfall of 1–2 cm raised the albedo from 0.39 to 0.78."
So my idea is to have windbreaks in the Arctic that spread snow evenly and prevent it from blowing away.
My Calculations on Arctic ice/snow, using equations from Fundamentals of Thermal-Fluid Sciences by Cengel and Turner:
1) Assume solar radiation (direct and diffuse) on snow or ice is 500 W/square metre. 2) Assume emissivity of snow or ice is 0.97.
3) Assume absorptivity of snow or ice changes from 0.6 to 0.2 when snow falls (albedo increases when snow falls and absorptivity decreases).
4) Assume the effective sky temperature is -20 deg C
5) Assume temperature of ice or snow is -5 deg C.
Then for absorptivity of 0.6 (low albedo) the ice/snow has a heat gain of 242 watts per square metre. For an absorptivity of 0.2 (high albedo) the ice/snow absorbs only 42 watts per square metre.
https://nsidc.org/cryosphere/seaice/characteristics/difference.html says, "Because the Arctic Ocean is mostly covered by ice and surrounded by land, precipitation is relatively rare. Snowfall tends to be low, except near the ice edge. Antarctica, however, is entirely surrounded by ocean, so moisture is more readily available. Antarctic sea ice tends to be covered by thicker snow, which may accumulate to the point that the weight of snow pushes the ice below sea level, causing the snow to become flooded by salty ocean waters."
Saturday, February 4, 2017
Rain from temperature differences.
I was reading http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap4.html
which says, "Such a large acceleration arising from only a modest temperature difference illustrates the importance of buoyancy in determining vertical transport in the atmosphere."
I am convinced that having lighter coloured areas round a city with a dark area in the middle one could get air rising fast and possibly get rain to fall when the air cools higher up. Example: The black inner area heats up 3 deg C more than the surrounding lighter coloured surroundings (very feasible) to say 30 deg C (surroundings at 27 deg C). Then this hotter air mass initially accelerates from the ground at about 0.1 m/s^2.
Later on, within a cloud formation, if there is a 3 deg C temperature difference, the hotter air can reach an upward velocity of about 9 m/s relative to the rest of the cloud (using an equation from a cloud physics text). On getting colder this rising air mass will cause more condensation. Could we use some fairly harmless dye to darken areas of the sea so that temperature of the dark area is one or two degrees higher than the surroundings and so cause rain. Could plankton be used to darken an area?
See also https://books.google.co.za/books?id=qvuODAAAQBAJ&pg=PA211&lpg=PA211&dq=terminal+velocity+of+buoyant+air+parcels&source=bl&ots=xabrJUxcYk&sig=cUKULxw49DpTUHnZvT3mTN-h3Ng&hl=en&sa=X&ved=0ahUKEwj4zPCHrvjRAhUlBsAKHYATDcIQ6AEILDAD#v=onepage&q=terminal%20velocity%20of%20buoyant%20air%20parcels&f=false
which says, "Such a large acceleration arising from only a modest temperature difference illustrates the importance of buoyancy in determining vertical transport in the atmosphere."
I am convinced that having lighter coloured areas round a city with a dark area in the middle one could get air rising fast and possibly get rain to fall when the air cools higher up. Example: The black inner area heats up 3 deg C more than the surrounding lighter coloured surroundings (very feasible) to say 30 deg C (surroundings at 27 deg C). Then this hotter air mass initially accelerates from the ground at about 0.1 m/s^2.
Later on, within a cloud formation, if there is a 3 deg C temperature difference, the hotter air can reach an upward velocity of about 9 m/s relative to the rest of the cloud (using an equation from a cloud physics text). On getting colder this rising air mass will cause more condensation. Could we use some fairly harmless dye to darken areas of the sea so that temperature of the dark area is one or two degrees higher than the surroundings and so cause rain. Could plankton be used to darken an area?
See also https://books.google.co.za/books?id=qvuODAAAQBAJ&pg=PA211&lpg=PA211&dq=terminal+velocity+of+buoyant+air+parcels&source=bl&ots=xabrJUxcYk&sig=cUKULxw49DpTUHnZvT3mTN-h3Ng&hl=en&sa=X&ved=0ahUKEwj4zPCHrvjRAhUlBsAKHYATDcIQ6AEILDAD#v=onepage&q=terminal%20velocity%20of%20buoyant%20air%20parcels&f=false
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