Wednesday, May 24, 2017

More drought as land gets hotter relative to the oceans

Local governments could check their cities for air temperature rise: says
"Global warming caused by human activities that emit heat-trapping carbon dioxide has raised the average global temperature by about 1°F (0.6°C) over the past century. In the oceans, this change has only been about 0.18°F (0.1°C). This warming has occurred from the surface to a depth of about 2,300 feet (700 meters), where most marine life thrives." that Cape Town was 1 deg C hotter than average. Geography books point out that warm air temperatures over land with cold sea temperatures usually mean low rainfall. It appears the difference between sea and land temperatures for Cape Town is becoming large at an unusually high rate. To repeat my previous ideas I think floating sea spray generators driven by waves to increase humidity over the sea and solar air heaters on roofs or in gardens in Cape Town to make air rise and cause convectional rain would be a cheap solution. The urban heat island effect can cause 10% more rain and I think my idea would have an even greater effect. 
Using :
Los Angeles was 0.9 deg C above normal.
Cape Town was 1 deg C above normal
Another problem: Land is getting less solar radiation and the lower atmosphere is heating because of the greenhouse effect: Personally I think cool roofs and cool pavements, etc, are making the situation worse. They prevent ground from getting hotter which reduces convection and makes pollution worse and rainfall less. If you increase convection with hotter surfaces you can get more clouds and clouds reduce solar energy falling on a city dramatically - you might get less than half the solar energy falling on a city if you have cloud formation. It seems that with global warming the following could be happening: With all the air pollutants put in the air by man, less solar energy is reaching the ground so the ground cannot warm up the air above it so much (this is discussed in physical geography books and so on). This reduces air temperatures near the ground and this increases relative humidity near the ground because relative humidity decreases with increasing temperatures unless moisture is added (and increases with reducing temperatures). Added to this, the lower atmosphere is warming because of the greenhouse effect. When air is heated by the ground it may rise, but it comes into contact with the heated air in the lower atmosphere and cannot rise so easily there because this air parcel heated by the ground needs to be hotter (less dense) than the surrounding air. Because of this less clouds form. To give credence to my theory look at the relative humidity near the ground and higher up in the diagram at The relative humidity at ground level has remained high throughout the years but is decreasing higher up. says, "the improved analysis shows that the atmospheric (lower troposphere) temperatures are warming faster than the Earth’s surface." For convectional rain to occur we need the Earth's surface to heat air above it so it can rise. Now the air is being heated less by the ground and when it tries to rise and cause convectional rain it comes into contact with hotter air, so it tends to sink and so does not tend to rise and cool so much, which could cause condensation and rain. One solutions is to make land darker with biochar, and so on, so it heats up more.

Tuesday, May 23, 2017

Rain and relative humidity

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

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.

Friday, May 19, 2017

Trees can increase air pollution - use air convection
"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