Wednesday, September 27, 2017

Creating rain using convergence of sea breezes

Some people will know more than me about sea breezes around Cape Town than I do, but Florida and other narrow land masses have sea breezes from both sides and there is an area of convergence where high pressure and rising air result where the two breezes meet. This is associated with high rainfall in areas such as Florida. Could one heat the middle of the Cape Peninsular by using biochar? The dark biochar soil will heat up more than the surrounding land and air above it will rise. Could this result in a situation similar to those they have in other areas of convergence, such as Florida? The sea round Cape Town is not as hot as the sea round Florida, but I bet one could increase rainfall by making land darker in the middle of the land area. Convergence and rain also occurs in New Zealand - see 
See also 
In summer in Florida rain occurs daily during some periods. A sea breeze is created by hot rising air over the land, wind blows in from both sides (two sea breezes) and the two air masses collide. Pressure is created where they collide and the air has only one place to go and that is upward. This rising air creates the frequent convectional rain mentioned. 

To dry out the air so that less hurricanes are formed in the Gulf of Mexico, put wide strips of solar air heaters in the Gulf to imitate a sort of very narrow Florida and create convectional rain that way to dry the air. The phenomenon of drying out of the air in tropical regions, because of frequent convectional rain, is discussed in "Understanding the sky" by Dennis Pagen - it can be found on the Internet - see

The United Kingdom has various air masses moving onto it. 1) Polar maritime air that has blown over the sea and is cold and moist. 2) Polar continental air that is cold and dry 3) Tropical maritime air that has blown over the ocean and is warm and moist 4) Tropical continental that is warm and dry 
 Question: Which of the above do you think brings both showers and thunderstorms?
 Answer: Although warm moist air holds a lot of moisture, when warm moist air is heated from the ground or ocean (this is the usual way air is heated - it is heated from below), it is not much warmer than the air above it (or the sea may be colder and cool the air from below) and not much upward convection (or no upward convection) occurs. With the cool moist polar maritime air (1 above), the air heated by the ground or ocean is hotter than the air above it and rises, so case 1 is the only option that provides both showers and thunderstorms (Reference: Aviation Law And Meteorology by Air Pilot Publishing Ltd).

Could one create rain using floating spray generators in the sea to humidify the air and floating solar air heaters to heat the moist air and cause convectional rain?
Example: Suppose sea and air temperature above the sea and over land is 20 deg C. Suppose the relative humidity (RH) is 60%. Then the wet bulb temperature is 15.21 deg C. If we assume fine mist evaporative cooling with an efficiency of 80%, then the evaporation of spray will cool the air down to 16.17 deg C. This is 3.83 deg C lower than the 20 deg C. With sea at 20 deg C and air at 16,17 deg C the air can be heated from below by the sea. This would simulate the situation in option 1. I calculate that 1.9 g of water needs to be evaporated into every cubic metre of air to result in a temperature lowering of 3.83 deg C. If the spray generators were permanent, a cooler micro-climate would result, but sea temperatures would stay more constant and convectional rain should occur. Calculating relative humidity (RH) after an 80% efficiency fine mist cooling, I get that RH=90% after evaporation. With such a high RH, if you heated an air parcel 2 deg C to 18.17 deg C, it could rise 606 m by virtue of being 2 deg C warmer, and it would only have to rise 456 m for cloud to start forming (used general sorts of lapse rates).
Previously I mentioned that when the sea was hotter than air temperatures, then from graphs, rain was more likely. This makes sense because then the air is heated from below by the sea, it will rise into the colder air and keep rising until it is at the same temperature as the surrounding air, and convectional rain should occur.

 AIR POLLUTION: I will quote you something from Aviation Law and Meteorology by Air Pilot Publishing LTD. It talks about rising air (which will result when solar air heaters heat air). "In a depression , the rising air will be cooling and so cloud will tend to form. Instability in the rising air may lead to quite large development of cumuliform cloud accompanied by rain showers. Visibility may be good (except in the showers), since the vertical motion will tend to carry away all the particles suspended in the air."

Friday, September 15, 2017

Cool Earth Using Evaporation says,
"�Earth’s surface lost heat to the atmosphere when water is evaporated from oceans to the atmosphere. �The evaporation of the 1m of water causes Earth’s surface to lost 83 watts per square meter, almost half of the sunlight that reaches the surface. �Without the evaporation process, the global surface temperature would be 67°C instead of the actual 15°C."
I am trying to convince scientists to implement the use of floating spray pumps to create evaporative fine mist cooling over the Gulf of Mexico and regions where the tropical storms form. It will prevent solar energy from entering the ocean and cool, preventing hurricanes from forming.To get convection and convectional rain, solar air heaters can be used to heat the moist air - I think it will save insurance companies billions. The whole mechanism of rain (evaporation and condensation) moves energy away from the surface to regions higher up. explains that evaporation increases low level clouds which reflect solar energy back to space. In fact low level clouds in low latitudes are comparatively warm and radiate heat back to space better than other clouds. Some scientists used to believe that more evaporation could even warm Earth because water vapour is a greenhouse gas. When they fed extra evaporation into climate models it showed that evaporation cools Earth.

Are warming sea temperatures making hurricanes worse?

One sees constant discussion about whether global warming is making hurricanes worse. There is a lot of rain with hurricanes, which means huge energy comes from the ocean. It takes about 2400 kJ to evaporate a kg (about a litre) of water and rain means there must have been evaporation in the first place. The energy for the evaporation comes almost entirely from the water, because air has such a small heat capacity that if the energy came from the air it would quickly be cooled. Air has a volumetric heat capacity of about 1.2 kJ per cubic metre for every 1 deg C drop in temperature. Water has a volumetric heat capacity of about 4180 kJ per cubic metre for every 1 deg C drop in temperature.  tells us that a hurricane has about 5.2x10¹⁹ J or 5.2x10¹⁶ kJ of energy per day spread out over about an area with radius 665 km. My calculations give that this is about 37429 kJ per square metre per day or 10.4 kWh per square metre per day. By comparison one may get about 8 kWh per day per square metre from the sun (Weatherspark will tell you how much for you area). If the energy is coming from the water, then one cubic metre of water (1000 kg) would be cooled 37429/(4180)=9 deg C in a day. So if we do not have deep hot water to provide the energy, the hurricane will lose strength. It seems obvious that warming sea temperatures will fuel hurricanes more, or have I missed something?

Monday, September 4, 2017

Air pollution solution calculations.

Air pollution solution calculations : Many people do not realise that there is a sufficient amount of solar energy to heat massive volumes of air every day. The problem is getting air to come into intimate contact with hot surfaces. The ground heats air immediately above it, but there is not intimate contact with large volumes of air. Solar air heaters provide large hot surface areas and intimate contact. See
Often about 7 kWh of solar energy fall on every square metre of surface in a day. This is 7x3600 kJ, which is 25200 kJ of energy. Air has a volumetric heat capacity of about 1.2 kJ/(deg C.cubic metre) and we might ask how many cubic metres of air we could heat by 5 deg C every day with the 25200 kJ? The answer is we can heat 25200/(5x1.2) cubic metres by 5 deg C in a day. We divided by 1.2 (volumetric heat capacity) and by 5 (the number of degrees the air is heated.). This is 4200 cubic metres that can be heated 5 deg C in a day by a 1 square metre solar air heater.This has great implications for diluting air pollution, for enhancing chances of convectional rain and for cooling cities. If we place a large number of solar air heaters above each other on a tall pole we could have massive heating of air.
 If the solar elevation angle is not 90 degrees, then we can do this without the one solar air heater casting a shadow on the one below. Only at midday, in equatorial regions, on two days a year, could we have a solar elevation angle of 90 degrees, so we can safely say it is possible not to have shadows cast on solar air heaters below, for the most part of the day and year, anyway. 
Another advantage of this is that we could cool cities like Kuwait city. Huge solar air heaters on the tall pole would shade parts of the city, the solar energy would go into heating the air, the air would rise and transfer heat to a higher altitude and Kuwait city would be cooler.
I had a hard time finding figures for the volumetric heat capacity of air. In fact I could not find a table so I made one.The figures will be useful for calculating how many cubic metres of air at a certain temperature and pressure of 101.325 kPa can be heated by a solar air heater, for example. 
I calculated the figures using Specific heat of mixture of gases=sum of (mass fraction x specific heat of each gas). I then calculated the mass of a cubic metre of air with RH=50% for various temperatures and multiplied specific heat by mass of a cubic metre of air with RH=50 and P=101.325 kPa at various temperatures. The RH makes very little difference to the volumetric heat capacity (although it does make a bigger difference to the specific heat in kJ/kg.degC.). For instance the volumetric heat capacity of dry air at 35 deg C at P=101.325 kPa=1.154 kJ/degC.m^3 and the volumetric heat capacity for an RH=50% parcel at the same temperature and pressure is 1.159 kJ/degC.m^3. 
The chart is for people living in cities on the coast. If you want a chart for your city, please give me altitude. If you want to do calculations on air pollution and convection then you can proceed as follows:
1) Find out how many kWh you receive in a day from Weatherspark Note that this Weatherspark figure is for a horizontal surface. If you let the solar air heaters face the sun you could get a lot more kWh of heat.
2) Decide on the area of your solar air heater and multiply (eg 100 sq metres and 6 kWh per sq metre per day. kWh=6x100=600 kWh. This is 600x3600 kJ (1 kWh=3600 kJ) ie this is 2160000kJ).
3) If you heat the air 5 deg C, then number of cubic metres heated in a day by 5 deg C = 2160000/(5xvolumetric heat capacity). You can get the volumetric heat capacity from the chart.
4) If the system is only 70% efficient, then multiply by 70/100=0.7.