Frost prevention, rain enhancement, air pollution dilution

Although I do not drink wine, I like grapes, and I read that grapes had been damaged by frost in France. Here is an idea: Have a long pipe running through the vineyards, with holes in to let out water vapour. Boil water at one end of the pipe (or at points along the pipe) and water vapour will come out all along the pipe into the vineyards. This will increase the sky temperature by increasing relative humidity and the greenhouse effect and help reduce frost.
Hot water vapour actually radiates heat. The book "Fundamentals of Thermal-Fluid Sciences" by Cengel and Turner says that a 1-metre thick layer of water vapor at 1 atm pressure and at 100 deg C emits more than 50% of the energy that a blackbody would emit at the same temperature. Energy will therefore be radiated to the vines.
Regarding cold lower valleys, what usually happens is that the cold air comes down the sides of a valley and sinks below the warmer air (which could be only 10 metres above it). Helicopters are used to mix the warmer air above with the colder air to warm up the air immediately above the ground and higher. This method would also cause mixing because the vapour coming out the pipe would be less dense than the air, causing it to rise and mixing warmer air above with the colder air. One could also ensure that the vapour comes out at fairly high pressure to ensure mixing. The system could be used to enhance convectional rain or dilute pollution in cities by means of convection (dirty air rises out of the city).

Bring rain and reduce air pollution.

Clean up cities and bring rain with solar energy: With global warming the land is heating up faster than the ocean in terms of temperature (although about 90% of the solar energy absorbed by Earth is going into the oceans). When this happens the relative humidity of the air decreases more when blowing from sea to land. One can have floating spray pumps in the ocean to increase relative humidity (the pumps could be operated by wave motion). Another method to get more rain is to have this sort of system near the sea: Where there is land not being used (say on rocky hills, etc) erect pipes a few metres in diameter and a few hundred metres high and reflect sunlight onto these pipes using mirrors. The air in the pipes will be heated and rise and convectional rain is far more likely than usual to occur. It should be very cheap system to implement without the need for machinery to operate it. The bottom part could consist of a greenhouse. Often one will get 6 kWh or so of sunshine per day on a one square metre horizontal surface. Theoretically at 101.325 kPa this could heat 3600 cubic metres of air by 5 deg C (just the solar energy on one square metre could do this) starting off with 24 deg C air. With a 5 deg C temperature difference one can expect about 600 cubic metres per second out of the pipe (tower) if it is 400 m high or so (to research this Google stack effect draft, etc). To supply the energy for heating the 600 cubic metres coming out one needs roughly 5x1.2x600 kJ of energy per second (volumetric heat capacity of air is about 1.2 kJ per cubic metre per deg C and temp rise is 5 deg C and volume is 600 cubic metres). If sun power is 0.5 kW/ sq metre then we need 5x1.2x600/0.5 square metres of radiated surface. ie we need 7200 square metres of radiated surface. Therefore we need an area of about 84 m by 84 metres to supply energy to heat 600 cubic metres of air by 5 deg C every second. Of course there will be heat losses, so a bigger area is needed. This device can also be used to move polluted air out of cities by convection.
Links: 1) Cool roofs could be reducing rainfall https://www.scientificamerican.com/article/cool-roofs-may-have-side-effects-on-regional-rainfall/
2) Colour of land could affect 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
3) Regarding cool roofs, etc, 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." 

If space is a problem then one could build a greenhouse with black floors to absorb solar energy and holes in the floors to let hot air rise through. See following diagram:

Air Cleaner

You can email me at millertrader@gmail.com
The blog owner T E Miller (Swayseeker), known as Eddie will not accept liability or responsibility for any problems arising from the use of this blog and its calculations. I try to provide good calculations and analysis, but cannot guarantee that there are no mistakes. Here is a site that tells you how to build your own solar air heater:
 http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm
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Have been doing the following calculations: Los Angeles (latitude 34.05 deg N) has a maximum (always facing the sun) 11.2 kWh of solar energy per square metre on a good day on 1 July. On a horizontal surface it has 8.8 kWh of solar energy per sq metre per day (assuming a sunny day). It takes about 1.2 kJ of solar energy to heat 1 cubic metre of air 1 deg C (volumetric heat capacity of air is about 1.2 kJ per cubic metre per 1 deg C temperature rise - depends on pressure, etc). I have done this for the first day of each month and give a graph of how much air could be heated 5 deg C by one sq metre of horizontal surface by solar energy in one day. These are theoretical values and solar air heaters are certainly not 100% efficient, but the volume is enormous. I have been promoting this idea in Africa, China, US, India, via the Internet, etc, and am hoping it will have a good effect on the world.
If people generally knew the following facts about air the world might have been been different: 
Air is very little affected by radiation (sun shining through it, radiation from fires, heaters and so on). But air is heated by coming into contact with hot surfaces (casing of heaters, hot tar and so on) and the hot ground heats air and causes upward movement of this less dense air on a grand scale. The ground only has fairly superficial contact with air. On the other hand a solar air heater (a sort of greenhouse with a solar absorber to heat up in the sun and large hot surfaces to make contact with the air) is a different matter - it will heat air efficiently and a solar air heater on each rooftop could get warm air rising and out of polluted cities and also cause more rain to fall when vapour condenses in the cooler regions. 
People make their own solar air heaters and I believe India and China, with their pollution, could get polluted air moving out of their cities with them. It takes about 1.2 kilojoules of solar energy to heat 1 cubic metre of air by 1 degree C and every second 0.8 kilojoules of solar energy can easily fall on every square metre of some locations at noon.
The graph shows the number of cubic metres of air in a day that can theoretically be heated 5 deg C, using solar energy falling on a square metre of horizontal surface in Los Angeles. The x-axis shows 1 July, 1 Aug, etc.
Wikipedia says that rain dust (alkaline rainfall deposits, caused by particles from Saharan dust, etc) could help combat acid rain. 
An idea of mine: If one had huge solar air heaters and put Saharan dust in them, the hot air could carry the alkaline dust into sulfur dioxide-polluted air and neutralize acidity.
Wikipedia also says," Acid rain does not directly affect human health. The acid in the rainwater is too dilute to have direct adverse effects. However, the particulates responsible for acid rain (sulfur dioxide and nitrogen oxides) do have an adverse effect. Increased amounts of fine particulate matter in the air do contribute to heart and lung problems including asthma and bronchitis." 
Therefore the rain itself is good, because sulfur oxides, etc, are washed out, improving health prospects (reducing asthma, etc). Rain also washes out ozone, so if one could neutralize rain and get more rain, that would generally be good.
Graph below: The number of cubic metres of air in a day that can theoretically be heated 5 deg C, using solar energy falling on a square metre of horizontal surface in Los Angeles. The x-axis shows 1 July, 1 Aug, etc.

Graphs

The first two graphs are for Cape Town, South Africa (lat 33.9 deg S). These two graphs show 
1) the solar energy falling per day on one square metre, maximum (always facing the sun - upper graph) and for a horizontal surface (lower graph). Solar energy in kWh 

2) the theoretical volume of air per day (cubic metres) that could be heated 5 deg C by a solar air heater of dimensions 1m by 1m always facing the sun (upper graph) and on a horizontal surface (lower graph).

The graph below is for Delhi, India. Lat 28.4 deg N. The graph shows the theoretical volume of air per day (cubic metres) that could be heated 5 deg C by a solar air heater of dimensions 1m by 1m on a horizontal surface. The x-axis shows 1 July, 1 Aug, etc. So on 1 July, in a day, the 1m by 1m solar heater on a horizontal surface in Delhi could heat 5241 cubic metres of air by 5 deg C.

Looking at temperatures and relative humidities for Delhi (India) and taking a low rainfall month of November, with an average RH of 55% and daily average temperature of 20.8 deg C, the graph uses figures as follows: The surrounding air temperature is 20.8 deg C and air is heated to the temperature shown on the T-axis (parcel of heated hotter air is at temperature T deg C), using solar air heaters. The line with the steeper slope shows the height to which the parcel will rise, using a dry adiabatic lapse rate of 9.8 deg per 1000 m rise and an environmental lapse rate of 6.5 deg C every 1000 m (fairly standard sort of figures). The line with less steep slope shows how high the heated air parcel must rise before clouds start to form (uses Espy's equation). When the parcel is heated to 28 deg C it will rise further than it needs to before clouds start to form. Before about 28 deg C it will not rise far enough for clouds to form. Actual lapse rates for Delhi would have to be taken into consideration for accurate conclusions. You can also work this out yourselves.I will tell you the near ground dew point for the parcel - it is 11.43 deg C. Espy's equation says, for clouds to form, the air parcel must rise 125(T-Tdew) where T is the near ground level temperature of the parcel and Tdew is the near ground level dew point of the parcel. As for how high it can rise, after it has risen 1 km, starting at T=27 deg C, say, the temperature of the parcel is 27-9.8 deg and the surrounding air is at 20.8-6.5 deg, etc. When the parcel and surrounding air are at the same temperature the parcel will stop rising (this is modified a bit because water vapour is less dense than air)