During the day, sand's radiation of the sun's energy superheats the air and causes temperatures to soar. But, at night most of the heat in the sand quickly radiates into the air and there is no sunlight to reheat it, leaving the sand and its surroundings colder than before.
The water kept in an earthen pot seeps into the small pores in the pot and evaporates from the surface of the pot. The heat required for evaporation is taken from the water inside the pot, thus cooling the water stored inside. This is the reason why on hot summer days water remains cool in the earthen pot.
When we put some acetone or petrol or perfume on our palms, it evaporates. During evaporation, particles of the liquid absorb energy from the surface of the palm to compensate for the loss of energy, making the surroundings cool.
Due to the large surface area of hot tea (or milk) taken in the saucer, the evaporation of hot tea (or milk) from the saucer is faster. The faster evaporation cools the hot tea (or milk) much more quickly making it convenient to sip (or drink). Hence, we are able to sip hot tea or milk faster from a saucer than a cup.
During summer, we normally wear light-colored cotton clothes. We sweat a lot in the summers. Cotton is a good absorber of water. Thus, it absorbs sweat from our body and exposes the sweat to the atmosphere, making its evaporation faster.
Explanation: All of these answers are correct, I learned all of this whenever I was in fifth grade.
