Precipitation is any moisture that falls from the atmosphere. The most common types of precipitation are rain, snow, sleet, hail, fog and dew. Clouds basically form when water vapour (moisture) in the atmosphere starts to condense into water droplets. Water vapour starts to condense when the atmosphere can hold no more water i.e. it is saturated. Warm air can hold more moisture than cold air, so when air starts to cool water vapour is more likely to condense. Therefore, the formation of clouds and rain is most likely to happen when air cools. The three main types of rainfall are frontal, relief and convectional. However, it is important to note that water vapour must have condensation nuclei to condense around.
Condensation nuclei: Basically a surface that water vapour can condense on. This might be a piece of dust or a tiny grain of sand.
Frontal rainfall: This happens when an area of cold air and area of warm air meet. The warm is less dense so is forced over the top of the cold air. As the warm air rises it starts to cool, as it cools it can hold less moisture so the water vapour starts to condense. The condensing water creates clouds and rainfall.
Relief rainfall: This happens when air runs into a mountain or hill. As the air meets the higher land it is obviously forced upwards. As it is forced up the air begins to cool, reducing the amount of moisture the air can hold and causing the water vapour to condense, creating clouds and rainfall.
Convectional rainfall: This happens when the ground warms the air above it. As the air above the surface warms it becomes light and starts to rise. As it rises it starts to cool, as it cools it can hold less moisture and the water vapour begins to condense, creating clouds and rain. Convectional rainfall is very common in tropical countries and is likely to happen in the afternoon once the air has had chance to warm , rise and condense.
Precipitation
Condensation nuclei: Basically a surface that water vapour can condense on. This might be a piece of dust or a tiny grain of sand.
Relief rainfall: This happens when air runs into a mountain or hill. As the air meets the higher land it is obviously forced upwards. As it is forced up the air begins to cool, reducing the amount of moisture the air can hold and causing the water vapour to condense, creating clouds and rainfall.
Convectional rainfall: This happens when the ground warms the air above it. As the air above the surface warms it becomes light and starts to rise. As it rises it starts to cool, as it cools it can hold less moisture and the water vapour begins to condense, creating clouds and rain. Convectional rainfall is very common in tropical countries and is likely to happen in the afternoon once the air has had chance to warm , rise and condense.