Wednesday, July 4, 2018

Heat waves and decreasing air density by increasing RH

If there is a heat wave and you are near the sea there is something one could do. During heat waves relative humidity (RH) is usually low and this gives an ideal opportunity to add water to the atmosphere. If you add water by evaporative cooling you cool the air and then the air cannot hold so much moisture. If you add moisture by heating a part of the sea surface the air stays hot and the RH and water content of the air can increase a lot. You can heat a part of the sea surface by having floating black mats in the sea. Now when you add water vapour to the air the air becomes less dense. When the air is hot and dry you can add so much water vapour to the air that it becomes a lot less dense than the surrounding air and will rise, probably punching its way through the heat wave dome and creating clouds and possibly causing convectional rain. Example: Assume P=1 atmosphere (101.325 kPa). Assume the air temperature is T=38 deg C and RH=20%. Then the density of the air is1129.0 grams per cubic metre. Now increase humidity so that RH=80% with T still at 38 deg C.The density of the air is now 1112.2 grams per cubic metre. If you heated the original air with T=38 deg C and RH=20% to 42.71 deg C its RH would fall to 15.56% and it would have density of 1112.2 grams per cubic metre. This is the same density as the air with T=38 deg C and RH=80%. So increasing the humidity from 20% to 80% has the same effect on density as heating the air from 38 deg C to 42.71 deg C.

Thursday, March 29, 2018

Heat sea and air to bring rain

Cape farmers were having trouble with frost and now there are problems with drought.
There are two things needed for convectional rain and those are 1) Moisture in the air 2) Upward convection of air. As to moisture you can place black sheeting in the sea off Cape Town to heat the sea and supply moisture - see
https://airartist.blogspot.co.za/2018/03/could-we-create-small-el-nino-close-to.html

As to convection, you could have tall poles with rigid black plastic "roofs" on to shade crops and heat up the air above the black plastic (which will get hot in the sun). The black plastic will work in an opposite way to "cool roofs" which reduce rainfall - see https://www.scientificamerican.com/article/cool-roofs-may-have-side-effects-on-regional-rainfall/

As to frost (winter is coming), have sheets of plastic, on the poles mentioned, that deflect wind downwards and keep mixing warm air into the cold air near the ground.

Saturday, March 24, 2018

Rain with biological heating simulation

Could we create a small El Nino close to Cape Town with black plastic sheets?  I have been reading some articles on the formation of El Nino and Wikipedia at  https://en.wikipedia.org/wiki/Mixed_layer says, "The depth of the mixed layer is thus very important for determining the temperature range in oceanic and coastal regions. In addition, the heat stored within the oceanic mixed layer provides a source for heat that drives global variability such as El NiƱo." 
Now another article says that chlorophyll causes the solar energy to be captured in the top layer of ocean and, despite strong winds, a shallow mixed layer of warm water 20 to 30 m deep persists on top of the ocean where there is chlorophyll (biological heating of the surface) - see 
https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2003JC002024 
I therefore maintain that my cheap black floating plastic sheets will keep a warm layer on top (simulating biological heating) and will enhance rainfall. Probably for 10 million rands or so one could have a huge grid of floating black plastic sheets, say 50 m apart, that would enhance rainfall.
Reminder of my black floating plastic sheets idea: 
Hot water floats on cooler seawater and does not mix easily. For rain enhancement have cheap rigid black plastic sheets with plastic floats on the side that allow the black sheet to remain a few centimetres below the water surface Have a hole in the middle of the rigid sheet to let seawater in and out slowly. The black plastic sheet will absorb the visible light energy and infrared from the sun and when it radiates heat the heat radiated will be in the infrared range ranging around about 10 microns or so in wavelength. That type of radiation is absorbed within mm of penetration of sea, so in effect you have a greenhouse heating up with solar energy, because a few mm of seawater above the sheet will not allow radiation to exit the sea. http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html tells us that absorption coefficients are around 1000 per cm for this situation. This means that the intensity of radiation from the black sheet will drop to 1% of its original intensity within 0.046 mm of penetration of the seawater above it.
The floating hot water will humidify and heat the air above it. This more humid less and dense air will rise increasing chances of convectional rain. These black sheets could float like so many boats on the sea outside drought areas. With 7 kWh of solar energy per square metre per day falling the black sheets could heat water above them, that is 1 m deep, by 6 deg C in a day.
https://journals.ametsoc.org/doi/full/10.1175/1520-0442(2004)017<1097:BHITEP>2.0.CO%3B2
​ also has interesting information about biological heating.


Tuesday, March 6, 2018

Cooling cities and enhancing convectional rain

Method to cool hot cities, decrease air pollution and bring convectional rain. How does a city get hot? Well the sun shines on outside walls of buildings and the walls heat up and radiate heat to all objects around. How could you stop this? If you place greenhouse plastic, on the outside of buildings, a few centimetres away from the walls, then the sun shines (with high frequency radiation from the hot sun) through the greenhouse plastic onto the walls which heat up. Now the low frequency infrared radiation from the hotter walls (cooler than the sun) cannot get out through the greenhouse plastic and so will not heat up people and other objects around the walls. Instead the air is heated up between walls and greenhouse plastic and convection causes it to rise. The walls thus become air-cooled and the heat is transferred to the air. The rising air will draw in cleaner air from the air surrounding the city, the chances of convectional rain will be increased (more than just from having the urban heat island effect) and the city could become cooler because of:
1) Virtually no infrared radiation from hot walls of buildings onto objects. There will be some radiation from the greenhouse sheeting, but sun shines through greenhouse sheeting without heating it much at all.
2) Air cooling
There will also be possible cooling from:
1) Cloud formation that will shade the city
2) Rain which cools.

Thursday, March 1, 2018

Simulating convergence of moist air masses.

Many parts of the world are experiencing water shortage. If one could use rain enhancement to grow plants in the desert and soak up carbon dioxide it could help reduce global warming and drought. After I sent out an idea on rain enhancement to the Australian Water Association they suggested I submit a paper of about 5000 words to them on it, so perhaps they see merit in the idea. The idea depends on the principle of narrow land masses that heat up during the day, causing air to converge from both sides, meet in the middle, and rise because of high pressure where they collide. Imagine high walls running parallel, about a kilometre apart that cross the narrow land mass. Now bend the parallel walls into a U with ends facing the most windy direction. The pressure at the U part will be high, simulating convergence of air. Place dark biochar on the ground between the walls so it heats up and heats the air. This U shaped apparatus could be built in areas like Cape Town where it is windy and it will simulate places like Florida where convergence causes heavy rain. It could be built cheaply with tall poles with fabric stretched between the poles. Sea breezes often have depth of only 300 metres or so, so 300 m high walls may suffice.
There is advantage with convergence of air masses over the usual sea breeze. With a sea breeze the cooler air from the sea lifts the drier hotter land air and when the drier land air rises clouds and rain can occur. With convergence of sea breezes moist sea air is forced to rise and the more moist air facilitates rain.


Wednesday, January 31, 2018

If coastal cities need more rain...

Can also visit https://www.facebook.com/groups/RainSeaVsAirT/
If coastal cities need more rain they could try heating water in greenhouses to add water vapour to the air. Here is a graph (below) using the average of six evaporation equations. You can get 20 or more times the evaporation by increasing water temperatures. 
Studies on evaporation from windy sea conditions show more rain with more evaporation of spray. 
In many cities you can evaporate over 100 000 litres every day with a 100m by 100m greenhouse and add it to the atmosphere, humidifying it and increasing chances of rain. 1kWh can evaporate about 1.5 litres and many cities can easily get about 8 kWh of solar energy on every horizontal square metre in a day.
When the air is hotter than the sea the water cools the air immediately above it and the relative humidity (RH) of this air increases and water can even condense out of the air so that "negative evaporation" occurs. If the seawater is hotter than the air the evaporation increases substantially, because the water heats the air above it, the RH of the air decreases, and the hotter air can take up moisture faster. This principle of high evaporation rate with water being hotter than air can be used to increase the humidity of the air and increase chances of rainfall. Therefore, heating seawater in greenhouses and so on can be very effective. Evaporation equations do not all give the same rate of evaporation and I use an average from six evaporation equations. Example: Wind speed=10 km/h, Air temperature above water is 32 deg C, temperature of water is 20 deg C, pressure = 1 atm. The average of the six equations is -1 mm per day so water condenses out and we could get a mist immediately above the water. Now we keep everything the same except we heat the water in a greenhouse to 37 deg C. The rate of evaporation (given by the average result of the 6 equations) is now 28 mm per day and we can increase the humidity of the air substantially, increasing chances of rain. Calculations show, if the area of greenhouses were one square kilometre, one could evaporate over 10 million litres a day in sunny areas.

Air tends to move back and forth with sea breezes and land breezes, so the humidity could accumulate every day from the greenhouse evaporation.
 BELOW IS A GRAPH SHOWING HOW EVAPORATION FROM THE SEA CAN BE INCREASED BY HEATING SEAWATER. INCREASED EVAPORATION MEANS INCREASED CHANCES OF RAIN:

Here is another graph (below) where air temperature is increased by only 1 deg C. So, as the air heats more relative to the sea, so the evaporation from the sea decreases. Decreased evaporation means decreased chances of rain.




Tuesday, January 9, 2018

Rain by humidification above the ocean.

Above shark nets, about 20 m above the ocean, have thick pipes with thousands of holes in that water streams out. Water can be pumped into the pipes using wind turbines. If the wind is blowing at 10 km per hour and the pipes are 1 km long, then the volume of air humidified in an hour is 1 km x 10 km x 0.02 km = 0.2 cubic kilometres.
In a day this is 4.8 cubic km of air. Nights are warmer with more humid air and I am going to use this as an example: RH=65% and Tair=20 deg C before humidification. RH=80% and Tair=22 deg C after humidification (the air will be blowing back and forth with land and sea breezes). Before humidification the water vapour content of the air is 11.2 grams/cubic metre and after humidification it is 15.5 grams/cubic metre. This is an increase of 38%. This relies on the fact that more humid air will keep in heat from the ocean when air is colder than the ocean. See 
http://www.asterism.org/tutorials/tut37%20Radiative%20Cooling.pdf

The heat from the ocean will help humidify. Air is usually colder than the ocean at night. During the day any mist will absorb solar energy and heat up and evaporation will occur. 

Thursday, January 4, 2018

Easy wet bulb temperature determination

People have been searching on the Internet for an easy way to calculate wet bulb temperature (and so have I). Experts give various long calculations and I wanted an accurate value easily calculated. I had a lot of trouble searching on various forums and eventually found a site that uses an equation that can be solved numerically that gives me an accurate answer, but the formula did not work unless I changed the P units from hectopascals to atmospheres. So instead of 1000 hPa I use 1000/1013.25. I solve numerically using a computer program I wrote to get Tw (wet bulb temperature). The formula is at
and I notice that P is included in one equation and left out in the next equation. However if you use atm it should work well with P included in both. The formula gives RH, but you can find Tw numerically. Say you are trying to find the wet bulb temperature for Td=45 deg C and RH=67%. Then let RHS=formula given and start with Tw=45 (represents RH=100%) and decrease Tw iteratively until RHS<=67. Find Tw at that point.

You can use a wet bulb calculator to check how accurate the above formula is (pretty good).
Your inputs into the program will be Td, RH and P. (P in atm). (Td is dry bulb T and Tw is wet bulb T.)

Code in Pascal:
Tw:=Td;
repeat
Tw:=Tw-0.001;
A:=611.2*exp(17.502*Tw/(240.97+Tw))-66.8745*(1+0.00115*Tw)*P*(Td-Tw);
B:=6.112*exp(17.502*Td/(240.97+Td));
RHS:=A/B;
until (RHS<=rh);

{Now print Tw}

Monday, December 25, 2017

Increasing sea surface temperatures and decreasing deeper ocean warming

As I expected there is a correlation between wind and rainfall. More wind then more rainfall. See
http://journals.ametsoc.org/doi/full/10.1175/JCLI3519.1
I propose that my idea of floating spray pumps, to create a spray mist on the sea, will have a similar effect as more wind. The spray mist will keep in heat radiated by the sea when sea is warmer than air and will generally tend to increase sea surface temperatures on clear nights. This will increase humidity and the chances of rain. Fortunately, during sunny days, the mist will prevent solar radiation from entering the sea and warming deeper levels of ocean.
Generally the mist will increase evaporation and enhance chances of rain. It will absorb solar energy during the day and heat up, again increasing chances of rain.
See also https://www.facebook.com/groups/RainSeaVsAirT/

Wednesday, December 13, 2017

Power coastal cities and cool oceans

Here is a way to provide power to cities on the coast and to cool the oceans to combat global warming. Usually the sea is warmer than the air at night. So at night use solar updraft towers, but pump heat, using a heat pump, from the sea to seawater in the solar updraft towers to heat and humidify the air in the solar updraft towers at night. Say the sea temperature was at Tsea=15 deg C and the seawater and air temperature in the solar updraft tower was 18 deg C after warming. Suppose the outside air temperature was 10 deg C. Then the heat pump would be very efficient and the air temperature difference between inside and outside the solar updraft tower would be in a nice range to start with. The heat pump could be powered by wind energy. During the day use the standard greenhouse at the base of the solar updraft tower to heat seawater in the tower to heat and humidify the air. The humid air will increase chances of rain and the clouds will reflect solar energy to space, cooling Earth. Have had a look at Greenland. It seems very suitable for this method. Ocean near the Arctic region could be cooled using this method. See
See
https://en.wikipedia.org/wiki/Solar_updraft_tower
See the the Carnot heat pump formula.at
 http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html
TH=291.15 kelvins. TL=288.15 kelvins

 COP=291.15/(291.15-288.15)=291.15/3 = 97.1

Saturday, December 9, 2017

Long greenhouse method to bring rain.

One could have a greenhouse to evaporate seawater near the sea and have a long greenhouse (or "greenhouse pipe") running upwards to where the dam areas are. Because the air will be kept warm during the day in the greenhouse pipe and moist air is less dense than drier air, the air will rush up through the greenhouse pipe and heat the dry air region and increase relative humidity there. Now it might seem that this would have little effect, but this system could be kept running day and night throughout the year. From my "stack effect" calculations quite a few cubic kilometres of warm moist air could be delivered every week to higher regions. The slight increase in relative humidity could just tip the balance enough to help it rain significantly more.
 More humid air is less dense than drier air, enabling it to rise when it is at the same temperature as  surrounding drier air: 
Example: 
1) At sea level the air pressure is 101.325 kPa. The air has a temperature of 30 deg C and the relative humidity (RH) is 95%. Then the density of the air is 1147 g per cubic metre.
2)  At sea level the air pressure is 101.325 kPa. The air has a temperature of 32 deg C and the relative humidity (RH) is 50%. Then the density of the air is 1147 g per cubic metre.
So humidifying the 30 deg C air by increasing RH from 50% to 95% has about the same affect on air density as heating the RH=50% and T=30 deg C air to T=32 deg C. 
Note: RH drops slightly on heating from 30 to 32 deg C, but it does not affect calculations much.

Tuesday, November 28, 2017

Rain when sea temperatures are greater than minimum air temperatures

Cape Town is one city where the minimum (night) temperatures are generally colder than the sea temperatures (see photo). This means that if you can create a spray over the sea with floating spray pumps at night you will have this situation: The warmer sea will have a spray "mist cloud" of low elevation over the sea. This cloud will capture radiation from the sea (greenhouse effect, with sea hotter than air above) and warm up, because clouds are good absorbers of infrared radiation. So at night the air will become warm and humidified. During the next day the land will heat up and a sea breeze will develop (at about midday). The warm moist air will blow onto land and the hot land will heat this moist air from below, increasing chances of rain. I am trying to get other countries interested in this concept, so perhaps South Africa will be able to observe what happens in other countries. 
See http://www.asterism.org/tutorials/tut37%20Radiative%20Cooling.pdf to gain insight to the radiation effect from the sea.
Many cities have this property.
See photo for Cape Town below.

Note that sea spray is natural and occurs in massive amounts when wind blows over the sea.

Tuesday, November 14, 2017

Water from seawater

Here is a method to make clean water from the sea: Geothermal heat pumps use ground as a heat sink. The air is cooled above and the heat pumped to the ground. 
To make clean water have a huge steel cylinder above the sea. Cool the steel using a heat pump that takes heat from the steel cylinder and puts the heat into the water. The heated water will evaporate into the steel cylinder and so the process will continue with water vapour condensing on the cool steel where it is collected. Solar energy could be also be used to heat the water below the steel cylinder. See https://en.wikipedia.org/wiki/Direct_exchange_geothermal_heat_pump
If a lot of solar energy were used to heat the water below the steel cylinder the heated water could also add more moisture to the surrounding air to slightly increase chances of rain.

Heat pumps are very efficient - you can get about 4 units of cooling with 1 unit of power. Wind, wave energy and batteries could be used to power the heat pump.
 If the air temperature inside the cylinder were 100 deg C and the cylinder walls were at a temperature of 80 deg C, the cylinder would cool by radiating heat and by being in contact with cooler air on the outside. This would enable increased condensation of water vapour on the cylinder walls.
Imagine a small scale system like this. If you use 1 kW of power to cool the cylinder you could get about 4 kW of cooling. So say you run it for an hour. Then you get 4kWh of cooling. It takes roughly 0.7 kWh to condense out a litre of water, so you should get about 4/0.7=5.7 litres an hour using power of 1 kW (assuming a coefficient of performance (COP) of 4). Note that as the water of the water heat sink evaporates it cools, making the system more efficient.

This whole system could be used in reverse to cool the sea and heat air in the cylinder. If the air were heated and seawater were sprayed in at the bottom, one could also create hot humid air and release it to the surroundings to increase chances of rain. One would need a huge cylinder and a lot of power to have a marked effect. With wind, wave and solar power it could work. Fortunately heat pumps do a lot of cooling or heating with a small amount of power (COP=4 or so).

COOLING THE SEA: If you can create cloud to shade the sea you can cool the sea down. Here is a method that will directly cool the sea and will cause convection above the sea by heating air above the sea. This will cause more clouds and rain. Rain cools the sea surface because it comes from cool regions higher up. Method: Use a heat pump to take water from the sea (sea is the fridge) and place it in some air cooled metal heat sink above the sea (fins of the fridge). The fins will warm the air causing upwards convection of warm air causing clouds and rain. Wind power could be used to power this heat pump. Heat pumps are very efficient and you can get about 4 units of cooling for 1 unit of input power - see https://en.wikipedia.org/wiki/Geothermal_heat_pump
Another desalination method I came across: https://atmocean.com