Give reason why:
(i) Earthen pots are wrapped with a wet cloth during summer?
(ii) We sweat more during humid climate?
(iii) Desert coolers are less effective during rainy season?
(iv) Evaporation causes cooling effect in a liquid?
(i) Earthen pots are wrapped with a wet cloth during summer?
(ii) We sweat more during humid climate?
(iii) Desert coolers are less effective during rainy season?
(iv) Evaporation causes cooling effect in a liquid?
Dear student,
(i) In the summer heat is maximum, and water evaporates from the wet cloth and makes it dry.The earthen pots are porous, taking the outside heat and make the cloth wet. This process of wetting and drying repeats and make the water in the pot remains cool.
(ii) It is actually not a matter of sweating more but of it being more difficult to evaporate the sweat. If you are in a dry and windy place it is very simple for sweat to evaporate, in a more humid area there is more water in the air already and therefore makes evaporation of the sweat much more difficult. Then it would appear that you sweat more because you are seeing the sweat, however, it is a matter of evaporation.
(iii) desert coolers are not effective during the rainy season because of the humidity present in the atmosphere. The atmosphere can hold a specific amount of water vapour in it. During the rainy season, the water vapor increases thus the water hilding capacity of the atmosphere is decreased. This causes humidity. Due to humidity, the desert cooler is not able to absorb heat.
(iv)
In evaporation, a substance changes its state from liquid to gas, for this process to occur energy in the form of heat is required (endothermic process) which has to be taken from some source (surroundings). So the source, which loses heat apparently becomes 'cooler'. Hence it can be said that evaporation causes cooling.
Regards
(i) In the summer heat is maximum, and water evaporates from the wet cloth and makes it dry.The earthen pots are porous, taking the outside heat and make the cloth wet. This process of wetting and drying repeats and make the water in the pot remains cool.
(ii)
It is actually not a matter of sweating more but of it being more difficult to evaporate the sweat. If you are in a dry and windy place it is very simple for sweat to evaporate, in a more humid area there is more water in the air already and therefore makes evaporation of the sweat much more difficult. Then it would appear that you sweat more because you are seeing the sweat, however, it is a matter of evaporation.
(iii) desert coolers are not effective during the rainy season because of the humidity present in the atmosphere. The atmosphere can hold a specific amount of water vapour in it. During the rainy season, the water vapor increases thus the water hilding capacity of the atmosphere is decreased. This causes humidity. Due to humidity, the desert cooler is not able to absorb heat.
(iv)
In evaporation, a substance changes its state from liquid to gas, for this process to occur energy in the form of heat is required (endothermic process) which has to be taken from some source (surroundings). So the source, which loses heat apparently becomes 'cooler'. Hence it can be said that evaporation causes cooling.
Regards
