Question

Why is it that with an increase in temperature of the air, the relative humidity will decrease even if the moisture content remains the same?

Answer 1

Relative humidity is the ratio of the amount of water vapour present in the atmosphere and the maximum amount of water vapour atmosphere can hold.
Now, with the increase in temperature the capacity of the atmosphere to hold the water vapour or moisture increases, thus decreasing the relative humidity. Hence, with an increase in the temperature of air, the relative humidity will decrease even if the moisture content remains the same.