Question

when is air moisture high in summer or in winter

Answer 1

Relative humidity is measure of moisture that air can hold.
Warmer the air more moisture it hold,which is directly proportional to rate of evaporation. In summers rate of evaporation is high, so air holds more moisture & thus relative humidity is high. Colder air cannot hold moisture & thus moisture gets condensed as dew .This is the major reason why we have dry skin in winter

Answer 2

During cold winter days water moisture in the outdoors air condenses and absolute humidity is low. In the summer moisture evaporates and remains in the air and absolute humidity is high. However the relative humidity (amount of humidity present compared with the amount possible at a given temperature) may easily be 100% in the summer or winter. The relative humidity is 100% at the dew point. During the winter cold dry outside air at a low dew point may enter a house and when heated will seem very dry and humidifiers are often required to maintain a comfortable relative humidity. In the winter the humidity cannot be maintained very high on very cold days because moisture will form frost on the insides of window panes and even on poorly insulated walls.