The amount of rainfall on our planet is uneven. In some areas, they fall regularly; other territories have not seen them for many years. How is the distribution of precipitation on Earth? What does it depend on?
Precipitation
Precipitation, which will be discussed in our article, are called atmospheric, or hydrometeors. In fact, it is water that falls out of clouds or precipitates on the Earth's surface in solid or liquid form. They are divided into cover, drizzle, rain.
The distribution of precipitation on Earth, frequency and intensity are the main characteristics that determine the climate. They can appear in the form of hoarfrost, rain, ice rain, snow, dew, hail, etc. They are measured by the thickness of the layer in millimeters. About 1000 millimeters of precipitation falls on average on the planet per year.
In different parts of our world, the number of hydrometeors is different. The greatest amount falls at the equator and in the temperate zones, in the tropics and polar regions, the least. The determining factors are atmospheric pressure above the surface, topography, location, and ocean currents. How are these phenomena responsible for the distribution of precipitation on Earth?
The role of air currents in the formation of precipitation
In many ways, the climate in different areas is determined by air masses. They are marine and continental and differ from each other in temperature and humidity. Sea currents form over the ocean, and continental over land, so they are drier and colder.
How is the distribution of precipitation on Earth? The role of air masses is associated with atmospheric pressure. It is not the same all over the planet, and is placed on its surface in alternating belts.
In temperate latitudes and at the equator, the pressure is low, and the Earth heats better. Warm air rises, and under the influence of cold layers of the atmosphere it falls again, but in the form of precipitation. The tropics and polar latitudes have high pressure, the air above them is dry, so there is little rainfall.
In addition, air masses constantly circulate between zones, the ocean and land in the form of cyclones, anticyclones, and winds. The monsoon from the sea provides heavy rains. Blowing from the land, it brings drought. Tropical trade winds and winds blowing from the east to the west bring the rains to the equator.
How does the location affect?
The specific location of the area has no less effect on the distribution of precipitation on Earth than other factors. The proximity of the area with the ocean is important, as some air masses, as well as sea currents, are formed here. Remoteness from the ocean can contribute to a drier and harsher climate, following the example of Eastern Siberia. Although, sometimes cold currents, on the contrary, provoke dry weather.
Geographic latitude is an important factor. Features of the shape of our planet contribute to the fact that its sections are heated unevenly. This, in turn, triggers the mechanisms of atmospheric pressure and air mass circulation. So, at the equator, the Earth heats up best, and therefore precipitation is more abundant than, for example, in temperate latitudes.
Sea currents
The proximity of some currents to the continents is also responsible for the distribution of precipitation on Earth. Depending on the temperature difference with the surrounding waters, the currents in the ocean are divided into warm, cold and neutral. The first two species affect climate and rainfall.
Warm currents carry water from low latitudes to high. Above them, the air heats up and evaporates, carrying precipitation to the coast. The Gulf Stream is the most powerful warm current in the world. It mainly affects the climate of temperate latitudes. For example, in Europe it softens the winter and increases the amount of precipitation (in Dublin up to 730 mm).
Cold currents move from high latitudes to lower ones. They bring a harsh and dry climate on the coasts, without letting in the warm and moist upper air masses. Under the influence of cold currents in temperate latitudes, on the western side of the continents, coastal deserts formed. Thus, the Peruvian current near Chile maintains the dryness of the Atacama desert, and the Bengal current - the Namib deserts in Africa.
Relief effect
Not a single climate-forming factor acts in isolation. The distribution of precipitation on the earth's surface depends on their joint work. The relief also matters. Mountains are able to retain moist air masses, plains, on the contrary, contribute to uniform distribution.
Sea winds from the oceans carry moist air. Turning into clouds, it falls in the rain or snow on the slopes of the mountains. So, the mountain slopes facing the wet winds receive rainfall, but delay them for opposite slopes and other territories of the continents.
Scandinavian grief, Cordillera, Andes serve as a barrier to westerly winds from the ocean, significantly drying out the continent’s climate and the eastern slopes of the mountains. The Alpine-Himalayan mountain belt receives precipitation from the equatorial monsoons from the south, but does not allow them to break further into the mainland.
The dry climate of central Australia is due to the barrier that creates the Great Dividing Range. Its eastern slopes provide significant precipitation with trade winds. Crossing the ridge, they overheat too much and cannot form precipitation.
Distribution of precipitation in Russia
The main territory of the country is characterized by a moderate amount of precipitation - up to 500 millimeters per year. The number is increasing in some southern regions, for example, in the Caucasus. Significantly reduced in the far North and in the steppes. Most precipitation falls in the summer. From west to east, with distance from the Atlantic Ocean, their abundance decreases.
The distribution of precipitation over the territory of Russia is determined by the action of temperatures, air circulation and topography. Westerly winds throughout the year bring precipitation to the Russian Plain, here they are most (up to 900 mm / g). The action of summer monsoon winds from the Pacific Ocean increases the amount of precipitation in the Far East. The driest zone is the Caspian lowland.
In winter, on the western slopes of the Ural Mountains, increased snowfall, compared with the eastern parts. It is also associated with the action of the Atlantic westerly winds. In summer, on the contrary, the eastern slopes of the mountains are full of precipitation.
Dry flows from the Arctic in the northern strip and dry continental air masses from the south contribute to the fact that a large amount of precipitation falls in the area between 55 and 65 latitudes. On both sides of this area they are much smaller.
Highscores
- The distribution of precipitation in the hemispheres follows the same principles, but in the Northern hemisphere a little less. This is due to the ocean, since it occupies a much larger area in the Southern Hemisphere.
- Precipitation is recorded in the Hawaiian Islands in the Pacific Ocean. There are up to 350 rainy days on Mount Wai Ali Ali.
- On the Chilean coast, near the city of Antofagasta, the average rainfall per year is less than 0.1 mm.
- For the title of the driest place on the planet, the Dry Valleys in Antarctica and the Atacama Desert in South America argue. In Antarctica, for example, some areas have not been wetted for more than two million years.
- Annually, the southern spurs of the Himalayas account for more than 10 thousand millimeters of precipitation. Which is ten times the average. The maximum mark was recorded in the town of Cherapundzhi in 1861, then 26,461 mm “rained”.