Relief rainfall is a type of precipitation that occurs when moist air is forced to rise over high land, such as hills or mountains. As the air rises, it cools and condenses, forming clouds and rain. Relief rainfall is also known as orographic rainfall, because it is influenced by the shape of the land (orography).
Relief rainfall is common in areas where the prevailing winds encounter high land, such as the west coast of the United Kingdom, the western slopes of the Andes in South America, and the western coast of New Zealand. These areas receive more rainfall than the areas on the other side of the high land, which are in the rain shadow. The rain shadow is an area where the air descends, warms, and becomes drier, resulting in less rainfall.
The following diagram shows the stages of relief rainfall formation:
– Stage 1: Warm, moist air from the ocean blows towards the high land.
– Stage 2: The air is forced to rise over the high land, cooling and condensing as it does so. Clouds form and precipitation occurs on the windward side of the high land.
– Stage 3: The air reaches the top of the high land and starts to descend on the other side, the leeward side.
– Stage 4: The air warms and becomes drier as it descends, reducing the chance of rainfall on the leeward side. This creates a rain shadow.
Relief rainfall is important for the climate and the environment of the areas where it occurs. It affects the temperature, humidity, wind, and vegetation of these areas. Relief rainfall can also cause erosion, landslides, and flooding on the windward side of the high land, and drought on the leeward side.
Relief rainfall is one of the three main types of rainfall, along with frontal rainfall and convectional rainfall. Frontal rainfall occurs when warm and cold air masses meet and form a front, causing the warm air to rise and cool, forming clouds and rain. Convectional rainfall occurs when the sun heats the land and the air above it, causing the air to rise and cool, forming clouds and rain.
To summarize, relief rainfall is rainfall that is caused by the rising of moist air over high land. It is also called orographic rainfall, and it creates a rain shadow on the leeward side of the high land. Relief rainfall is influenced by the shape of the land and the direction of the wind, and it affects the climate and the environment of the areas where it occurs.
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Relief Rainfall Diagram image
