Rain to cool things off

Say your city is close to the sea and humidity over the sea has been increased by the use of shallow pools with dark bottoms (shallow pools heat up more in sunny weather than deep sea), floating spray generators that use wave motion and floats on arms that drive spray pumps, and so on. When the moist air from the sea moves onto land one needs a way to make the air rise so that it can cool and clouds can form. Generally air does not heat up much by radiation. Below about 10 km altitude air is warmed by contact with the hot ground, mixing, and if it has a lot of moisture in it is heated a little by water vapour absorbing infrared radiation from the ground.
But air can be heated far more efficiently and in massive volumes by using solar air heaters. This is because solar air heaters let air come into close contact with large hot surfaces.
http://www.builditsolar.com/Experimental/PopCanVsScreen/PopCanVsScreen.htm will explain this concept.
The solar air heater can be at least 50% efficient. This means that if 10 kWh per square metre of solar energy falls on it in a day, each square metre of the solar air heater can provide at least 5 kWh of energy to heat the air. It only takes about 1.2 kJ of energy to heat 1 cubic metre of air by 1 deg C (the volumetric heat capacity of air is about 1.2 kJ per cubic metre per deg C). In 1 kWh there are 3600 kJ so large volumes of air can be heated by each kWh of solar energy.
With solar air heaters on every roof of a city and in other places near the ground one can get the moist air from the sea to rise when there is a sea breeze (breeze from the sea onto the land). The air will rise and cool until it is at the same temperature as the surrounding air. If it rises far enough it will cool enough for clouds and rain to result.
For an imaginary city at latitude 25 degrees North you will have approximately this situation on sunny days:
1) On 1 January, 4.0 kWh of solar energy falls on one square metre of a horizontal surface on that day and 1518 cubic metres of air can be heated by 8 deg C by that one square metre (assuming 100% efficiency).
2) On 1 February, 4.8 kWh of solar energy falls on one square metre of a horizontal surface on that day and 1791 cubic metres of air can be heated by 8 deg C by that one square metre (assuming 100% efficiency).
Carrying on in this way I have drawn a graph of how many cubic metres of air can be heated by 8 deg C in a day by one square metre of solar air heater (assuming 100% efficiency).

So with solar air heaters huge volumes of air can be heated to high temperatures. The hot ground cannot do this nearly as well because the air only has contact at ground level.

Summary: Air can be made moist and the moist air can be heated efficiently by solar air heaters and made to rise so that rain results.