Humidity refers to the amount of water vapour in the air. When water evaporates from bodies of water or moist surfaces, it turns into water vapour and mixes with the air. The amount of water vapour that air can hold depends on its temperature and pressure. Warm air can hold more water vapour than cold air. When the air is saturated with water vapour, any additional water vapour will condense into tiny water droplets and form clouds, mist or fog. So, humidity is not the same as cloud cover or mist, but rather the amount of water vapour present in the air.