Sunday, November 27, 2016

Bringing rain with seawater spray pumps

My guess is that with global warming there are going to be more droughts. The land heats up faster than the sea and if the land is warmer than the sea then air coming from the sea heats up and its relative humidity falls. Example: Air comes off the sea with relative humidity of 70% and temperature at 20 deg C and heats up to 25 deg C over land. The relative humidity drops to 52% and low relative humidity is associated with low rainfall. One needs to get air from the sea flowing over land as it brings moisture. Cold air tends to be denser and so cold air from the sea has more of a chance of flowing onto land. So here is the idea: 1) Make air over the sea fairly cold and very moist so it will tend to move in over land and bring moisture. 2) Over land, heat this air up so it will rise and vapour will condense, making rain.
You can do all this as follows: Use spray pumps operated by waves in the sea to form a mist that is evaporated in sunlight, causing air to be very moist and also cool (because of evaporation). Now use a solar air heater on every rooftop to heat this air when it comes onto land, so it will rise causing rain. Every two seconds one can have 1.2 kJ of solar energy falling on every square metre in many locations and this 1.2 kJ can heat one cubic metre of air 1 deg C. You could move massive volumes of moist air up like this. Another advantage is that low level clouds (and I would think mist) is associated with cooling of Earth. So you should have cooler Earth and more rain.
EXAMPLE: Say you have a 2km stretch of coast with the spray pumps (operated with wave motion). Let the air temperature over this stretch be 18 deg C with a relative humidity of 95%. Suppose the 2 km wide air parcel from the sea blows onto land. If you heat this 18 deg parcel up to 26 deg C with solar air heaters the relative humidity of the parcel falls to 58.3%. Suppose the surrounding air over the rest of the land area (surrounding the 2 km wide parcel) is at 22 deg C. Then the parcel can rise 1212 m (using a fairly standard dry adiabatic lapse rate). Using Espy's equation it only has to rise 1102 m for clouds to form, so it could rain.

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