Give a geographical reason for each of the following:

(i) The total volume of water in the oceans and seas remains constant.

(ii) In Equatorial regions the sky often remains overcast with clouds.

(iii) When relative humidity is 100% the temperature reading on both wet and dry thermometers is the same.

(i) The total volume of water in the oceans and seas remains almost constant because the water lost through evaporation is returned by precipitation directly into the oceans and indirectly through rivers and surface run-off. This continuous water cycle maintains the overall balance.

(ii) In the Equatorial region, intense heating causes warm, moist air to rise by convection. As it rises, it cools and condenses to form cumulonimbus clouds, keeping the sky overcast and producing frequent afternoon rainfall.

(iii) When the relative humidity is 100%, the air is fully saturated with water vapour. Since no evaporation takes place from the wet bulb, there is no cooling, and both the wet-bulb and dry-bulb thermometers record the same temperature.