Chapter 3 Weather and Climate Section 3: Variation and Distribution of

Section 3: Variation and Distribution of Precipitation

Changes in precipitation: Rain, snow and hail falling from the atmosphere are collectively referred to as precipitation. Precipitation has an important impact on human production and life.

Rainfall is the main form of precipitation. According to the amount of rainfall per unit of time, the meteorological department classifies rainfall into different levels such as light rain, medium rain, heavy rain and heavy rain.

In a region, the amount of precipitation varies from month to month during a year. A histogram of monthly precipitation is usually used to show the seasonal variation of precipitation in a region during a year. In addition, the amount of precipitation in a region varies from year to year.

Distribution of precipitation: Around the world, some places receive more precipitation and some places receive less. The distribution of precipitation is usually shown on an isopleth map. In an isoprecipitation line map, the amount of precipitation at each point on the same isoprecipitation line is equal. The general rules of annual precipitation distribution in the world are: more precipitation near the equator; less precipitation in the polar regions; less precipitation on the west coast of the continent and more precipitation on the east coast of the continent on both sides of the Tropic of Cancer; more precipitation in the mid-latitude coastal areas and less precipitation in the inland areas.