Question

how persiperation causes cooling effect and give the long answer

Answer 1

latent heat of vapourisation

Answer 2

It is the process of a liquid turning into a gas. When water is heated, it evaporates. The molecules move and vibrate so quickly that they escape into the atmosphere as molecules of water vapour. Water in the open - such as ponds, and lakes - needs to absorb energy to change phases from liquid to gas, that energy comes from the surrounding air, which then cools the air.

The best example is 'sweating'. When the external temperature of your body reaches 37°C or above, your body recognizes that the temperature in the surrounding air is higher than the temperature in your body, it’s time to perspire. The sweat evaporates from your skin using a little bit of your body heat and so you feel cool.