If the wet bulb temperature exceeds about 35 deg C (severe heat wave conditions) then people could die within hours. One can drink cold drinks and use air conditioning and so on. Here is a device (see drawing below) to cool oneself with (or cool a group of people with). Anyone may manufacture this device and sell it, but please give me 0.5% (only half of 1%) of your profits if you manufacture and sell this device. I have not seen such a device anywhere else. For evaporative cooling calculations please contact me. I will also do simple radiation calculations related to this device. Theoretically the bottom wet surface could be cooled by wind to the wet bulb temperature (which will be below ambient air temperature unless the relative humidity is 100%). This cooler surface will radiate less infrared radiation. So people below will be air-cooled and also receive less heat radiation. Usually the relative humidity in heatwaves is low (perhaps 20%). The lower the relative humidity the more evaporative cooling you can get. Calculation: Say air temperature is 40 deg C and the relative humidity is 25% with atmospheric pressure of 100 kPa and the efficiency of evaporative cooling is 60% (in ideal conditions it would be 100%). Then the wet bulb temperature will be 23.8 deg C, the volumetric heat capacity of the air before cooling will be 1.124 kJ/(m^3.degC), the air will be cooled to 30.3 deg C and the mass of water evaporated to do the cooling will be 4.4 grams per cubic metre of air cooled to 30.3 deg C.
Here is a device (see drawing below) that can be fitted to roofs or made into a large "umbrella" shading device for the garden. Anyone may manufacture this device but please give me 0.5% (half of a percent only) of your profits if you manufacture and sell this device or similar device. I have not seen this device anywhere else. It could be substituted as a cheaper alternative to the device at the top of this group (three-sheet device). The basic principle depends on this: In the sun the top surface heats up a lot (perhaps to 20 deg C above the ambient air temperature). When the device is given a tilt air rises by natural convection between the two surfaces, cooling the device. The temperature of the upper surface is thus reduced and the upper surface of the device radiates less heat than if it were a single surface left in the sun. Since the device shades the ground you get less heat radiation from the ground and there will be an overall cooling effect for people under and near the device.
