Relative humidity is simply the amount of water vapor
in the air in relation to how much water vapor that air can hold.
Colder air cannot hold as much water vapor as warmer air. Thus, as temperature decreases, the relative humidity will increase, and likewise, as temperature increases, the relative humidity will decrease.
The warmer the air, the more water vapor it can hold, the higher the RH
Relative Humidity is a ratio of the air's actual water-vapor content compared with the amount of water vapor air can hold at that temperature and pressure.
As the temperature goes up, the relative humidity goes down. The warmer the air is, the more water it can hold(the water is in vapor form). Say its 70 degrees outside, and the relative humidity is 50%. This mean that the air is currently holding half of the water it can contain. Say the temperature goes up to 80 degrees, but the actual amount of water in the air stays the same. The warmer air can now hold more water, so the relative humidity would now be under 50%. So if its 70 and there is 80% relavitve humidity, its less humid than if its 80 and there is 80% humidity..