Precipitation formed. Distribution of precipitation on the surface of the globe
Precipitation - water in a liquid or solid state that falls from clouds or precipitates directly from the air onto the surface of the Earth. These include:
Rain. The smallest droplets of water, with a diameter of 0.05 to 0.1 mm, that make up the clouds, merging with each other, gradually increase in size, become heavy and fall to the ground in the form of rain. The stronger the ascending jets of air from the sun-heated surface, the larger the falling drops should be. Therefore, in the summer, when the surface air is heated by the earth and rapidly rises, rain usually falls in the form of large drops, and in the spring and autumn - drizzle. If the rain falls from stratus clouds, then such rain is continuous, and if it is from kunevo-rain, it is torrential. It is necessary to distinguish drizzle from rain. This type of precipitation usually falls from stratus clouds. The droplets are much smaller in size than raindrops. The speed of their fall is so slow that they appear suspended in the air.
Snow. It is formed when the cloud is in air with a temperature below 0°. Snow is made up of crystals various forms. The most snow falls on the slopes of Rainier (state) - an average of 14.6 m annually. This is enough to fill a 6-story house.
hail. It occurs when there are strong upward air currents in warm time of the year. Droplets of water, falling to great heights with air currents, freeze, and ice crystals begin to grow on them in layers. The drops become heavier and begin to fall down. When falling, they increase in size from merging with drops supercooled water. Sometimes the hail reaches the size chicken egg, usually with different layers of density. Typically, hail falls from powerful cumulonimbus clouds during rainfall. The frequency of hail varies: temperate latitudes it happens 10-15 times a year, on land, where there are much more powerful updrafts, - 80-160 times a year. Hail falls less frequently over the oceans. Hail causes great material damage: it destroys crops, vineyards, and if the hailstones are different large size, then it can cause the destruction of houses and the death of people. In our country, methods for identifying hail clouds have been developed and hail control services have been created. Dangerous clouds“shoot” with special chemicals.
Rain, snow, and hail are called hydrometeorites. In addition to them, precipitation also includes those that are deposited directly from the air. These include dew, fog, frost, etc.
Dew(Latin ros - moisture, liquid) - precipitation in the form of water droplets deposited on the surface of the earth and ground objects when the air cools. In this case, water vapor, cooling, changes from a state to liquid and settles. Most often, dew is observed at night, in the evening or early in the morning.
Fog(turk, darkness) is an accumulation of small water drops or ice crystals in the lower part of the troposphere, usually near the surface of the earth. visibility is sometimes reduced to several meters. Advective fogs are distinguished by their origin (due to the cooling of warm humid air over more cold surface land or water) and radiation (formed as a result of cooling earth's surface). In a number of regions of the Earth there are often fogs on the coasts in places where cold currents pass. For example, Atacama is located on the coast. Cold weather passes along the coast Peruvian Current. Its cold deep waters contribute to the formation of fogs, from which drizzle settles on the coast - the only source of moisture in the Atacama Desert.
Water that falls on the surface of the Earth in the form of rain, snow, hail, or is deposited on objects in the form of condensation as frost or dew is called precipitation. Precipitation may be heavy, associated with warm fronts, or showers associated with cold fronts.
The appearance of rain is caused by the merging of small droplets of water in a cloud into larger ones, which, overcoming the force of gravity, fall to the Earth. If the cloud contains small particles solids(dust particles), the condensation process proceeds faster, since they act as condensation nuclei. When negative temperatures Condensation of water vapor in the cloud causes snow to fall. If snowflakes from the upper layers of the cloud fall into the lower layers with a higher temperature, where they contain a large number of cold drops of water, then snowflakes combine with water, losing their shape and turning into snowballs with a diameter of up to 3 mm.
Precipitation formation
Hail forms in the clouds vertical development, characteristic features which is the presence of positive temperatures in bottom layer and negative ones - in the upper one. In this case, spherical snowballs with ascending air currents rise to the upper parts of the cloud with more low temperatures and freeze to form spherical pieces of ice - hailstones. Then, under the influence of gravity, the hailstones fall to the Earth. They usually vary in size and can range in diameter from a pea to a chicken egg.
Types of precipitation
Such types of precipitation as dew, frost, frost, ice, fog are formed in the surface layers of the atmosphere due to the condensation of water vapor on objects. Dew appears when more high temperatures, frost and hoarfrost - when negative. When there is an excessive concentration of water vapor in the surface atmospheric layer, fog appears. If the fog mixes with dust and dirt in industrial cities, it's called smog.
Precipitation is measured by the thickness of the water layer in millimeters. On average, our planet receives approximately 1000 mm of precipitation per year. To measure the amount of precipitation, a device such as a rain gauge is used. For many years, observations have been made of the amount of precipitation in different regions planets, thanks to which they were established general patterns their distribution over the earth's surface.
Maximum precipitation is observed in equatorial belt(up to 2000 mm per year), minimum – in the tropics and polar regions(200-250 mm per year). IN temperate zone average annual quantity precipitation is 500-600 mm per year.
In every climatic zone There is also unevenness in precipitation. This is explained by the terrain features of a certain area and the prevailing wind direction. For example, on the western outskirts of the Scandinavian mountain range 1000 mm falls per year, and in the eastern regions - more than half as much. Areas of land have been identified where there is almost no precipitation. These are the Atacama Desert, the central regions of the Sahara. In these regions, the average annual precipitation is less than 50 mm. Great amount precipitation is recorded in southern regions Himalayas, in Central Africa(up to 10,000 mm per year).
Thus, the defining features of the climate of a given area are the average monthly, seasonal, and average annual precipitation, its distribution over the Earth’s surface, and intensity. These climate features have significant influence on many sectors of the human economy, including agriculture.
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