Sudha hangs up washed clothes to dry, in the courtyard. On a sunny and windy day clothes dry faster than on cloudy or days without wind. Analyse the reason for it.

The drying of clothes is facilitated by two main factors: heat and wind.

1. Heat: On a sunny day, the heat from the sun increases the temperature of the clothes and the water in them. This added heat helps to evaporate the water faster. Evaporation is a process where water changes from its liquid state to a gaseous state, also known as water vapor. The higher the temperature, the faster the rate of evaporation, hence, the clothes dry faster.

2. Wind: Wind aids in the drying process by blowing away the moisture-laden air surrounding the clothes. When clothes are wet, the water in them starts to evaporate. This evaporation causes the area around the clothes to become more humid. If this humid air is not removed, it slows down the rate of evaporation. Wind helps in blowing away this humid air and brings in drier air, which can absorb more water vapor, thus speeding up the drying process.

On a cloudy or windless day, both these factors are reduced. There is less heat from the sun to aid in evaporation, and without wind, the humid air stays around the clothes, slowing down the drying process. Therefore, clothes dry faster on a sunny and windy day compared to a cloudy or windless day.