Monsoons: winds, rains, currents. Monsoon climate region, wet and variable monsoon forests

Monsoon is often associated with heavy rains, hurricane or typhoon. This is not entirely true: the monsoon is not just a storm, but rather a seasonal movement of wind over an area. As a result, there may be heavy summer rains and drought at other times of the year.

What causes monsoons?

Monsoons (from the Arabic mawsim, meaning "season") are caused by temperature differences between land and ocean, explains the National Weather Service. The sun warms the earth and water differently, and the air begins to “tug of war”, and the colder one wins, humid air from the ocean. At the end of the monsoon period, the winds reverse.

Wet and dry monsoons

Wet monsoons usually arrive at summer months(from April to September), bringing heavy rains. On average, about 75% of annual rainfall in India and about 50% in the region North America(according to NOAA research) falls during the summer monsoon season. As mentioned above, wet monsoons bring ocean winds to land.

Dry monsoons occur in October-April. Dry air masses come to India from Mongolia and northwestern China. They are more powerful than their summer counterparts. Edward Guinan, professor of astronomy and meteorology, states that the winter monsoon begins when "the land cools faster than the water and a high blood pressure, displacing ocean air." Drought is coming.

Winds and rains

Every year the monsoons behave differently, bringing either light or heavy rains, as well as winds of varying speeds. The Indian Institute of Tropical Meteorology has compiled data showing the annual monsoon in India over the past 145 years. The intensity of the monsoons appears to vary over 30-40 years. Long-term observations show that there are periods with weak rains, one of which began in 1970, and others with heavy rains. Current records for 2016 showed that from June 1 to September 30, precipitation amounted to 97.3% of the seasonal normal.

The heaviest rainfall occurred in Cherrapunji, Meghalaya state in India, between 1860 and 1861, when the region received 26,470 mm of rainfall. The area with the highest average annual amount (observations lasted for 10 years) is also in the state of Meghalaya, where the average rainfall was 11,872 mm.

Where do monsoons occur?

The places where monsoons occur are the tropics (between 0 and 23.5 degrees north and south latitude) and the subtropics (between 23.5 and 35 degrees north and south latitude). The strongest monsoons are usually observed in India and South Asia, Australia and Malaysia. Monsoons occur in the southern regions of North America, Central America, northern regions South America, as well as in West Africa.

Monsoon influence

Monsoons play in many areas globe determining role. Agriculture Countries like India are heavily dependent on the monsoon. According to National Geographic, hydroelectric power plants also schedule their operations depending on the monsoon season.

During periods when the world's monsoons are limited by weak rains, crops do not receive enough moisture and farm incomes decline. Electricity production decreases, which is only enough for the needs of large enterprises, electricity becomes more expensive and becomes inaccessible to poor families. Due to the lack of domestic food products, imports from other countries are increasing.

During periods of heavy rain, floods are possible, causing damage not only to crops, but also to people and animals. Excess rain contributes to the spread of infections: cholera, malaria, as well as stomach and eye diseases. Many of these infections are spread through water, and overloaded water facilities are unable to clean water for drinking and household use.

The North American monsoon system is also driving a fire season in the southwestern United States and northern Mexico, NOAA said, due to an increase in lightning caused by changes in pressure and temperature. Some regions experience tens of thousands of lightning strikes overnight, causing fires, power outages and severe injuries in people.

Monsoons and global warming

A group of scientists from Malaysia warns that due to global warming we need to expect an increase in precipitation during the summer monsoons in the next 50-100 years. Greenhouse gases such as carbon dioxide, help keep you in the air more moisture that rains down on already flooded areas. During dry monsoons, the land will dry out more due to increased air temperatures.

On small time scales, rainfall during the summer monsoon may vary due to air pollution. El Niño (fluctuations in surface temperature Pacific Ocean) also affects the Indian monsoon in both the short and long term, say researchers from the University of Colorado Boulder.

Many factors can influence the monsoon. Scientists are doing their best to predict future rain and winds - the more we know about the behavior of the monsoon, the sooner preparations can begin.

When approximately half of India's population is engaged in agricultural work and agronomy accounts for approximately 18% of India's GDP, shifts in monsoon timing and rainfall can cause great challenges. But research conducted by scientists can turn this problem into a solution.

Who among us in childhood did not read adventure books about distant journeys, noble sailors and fearless pirates?


When we pronounce the words “monsoon” and “trade wind”, we bring to mind precisely these romantic pictures: distant tropical seas, uninhabited islands, covered with lush greenery, the clanking of swords and white sails on the horizon.

Meanwhile, everything is much more prosaic: monsoons and trade winds are well-known names that have a significant impact on the formation of weather not only in tropical areas, but throughout the planet.

Monsoons

Monsoons are winds with a stable direction, characteristic of tropical zone and some coastal countries Far East. IN summer time Monsoons blow from the ocean towards land, and in winter - in the opposite direction. They form a peculiar type of climate called monsoon, characteristic feature which is high level air humidity in summer period.

One should not think that in areas where the monsoon prevails, there are no other winds. But winds from other directions appear from time to time and blow for short periods, while the monsoon is the predominant wind, especially during winter and summer. The autumn-spring periods are transitional; at this time, the stable wind regime is disrupted.

Origin of the monsoons

The appearance of monsoons is entirely related to the annual cycles of distribution atmospheric pressure. In summer, the land heats up more than the ocean, and this heat is transferred to the lower atmospheric layer. The heated air rushes upward, and a zone is formed over the land low blood pressure atmosphere.

The resulting lack of air is immediately filled with a colder air mass located above the ocean surface. It contains large number moisture evaporated from the water surface.

Moving towards land, air from the sea carries this moisture and sheds it on the surface of coastal areas. Therefore, the monsoon climate is wetter in summer than in winter.

With the coming winter period the winds change their direction, since at this time the land surface warms up less actively, and the air above it turns out to be colder than above the sea surface, which explains the change in the direction of the monsoon at this time.

Geography of the monsoons

Monsoon climate is most typical for the equatorial regions of Africa, the northern coast of Madagascar, many countries of Southeast and South Asia, as well as the equatorial part Southern Hemisphere, including the northern coast of Australia.

The Caribbean states are affected by the monsoons. southern part Mediterranean Sea and some other areas, but in a weaker form.

Trade winds

Trade winds are winds that blow steadily in tropical zone all year round due to the inertial force of the Earth's rotation and climatic features tropics.


In the Northern Hemisphere, trade winds blow from the northeast, and in the Southern Hemisphere, from the southeast. The trade winds are most stable over the sea surface, while the land topography introduces certain changes in their direction.

The name "passat" comes from the Spanish expression "viento de pasada" - wind that favors movement. In the era of the Great geographical discoveries, when Spain was the queen of the seas, the trade winds served as the main factor favoring the movement sailing ships between the European continent and the New World.

How are trade winds formed?

Equatorial zone our planet is experiencing the most intense warming sun rays, therefore the air in the lower layer of the atmosphere always has enough high temperature. Because of this, there is a stable upward air flow in areas close to the equator.

In place of the rising air, colder air masses immediately rush from both subtropical zones– northern and southern. Thanks to the Coriolis force - the inertial force of the Earth's rotation - these air currents do not move strictly in the southern and northern directions, but are deflected, acquiring a southeastern and northeastern direction.


The cold air that rises cools and falls down, but due to the outflow of air in the northern and southern temperate zones he rushes there and also experiences the action of the Coriolis force. These winds blowing in upper layers atmosphere are called upper trade winds, or counter-trade winds.

Geography of trade winds

The trade winds are prevailing winds all along equatorial belt, except coastal zone Indian Ocean where they are in force geographical features coastline turn into monsoons.

SUMMER MONSOON - a moist wind from the ocean towards a warmer continent. In San Francisco, this is what they call a sea day. , penetrating through the Golden Gate sometimes 150 km into the interior of the continent, to the confluence of the San Joaquin and Sacramento rivers. Accompanied by a cooling of 5-8 "C. Intensifies with intense heating of the Big Valley. Brings fog to the continent (see. ), arising above the cold California Current, forming a “sea of ​​clouds” over the Golden Gate, while at an altitude of 700 m the mountain slopes are brightly illuminated by the Sun. Thanks to the L.M. in San Francisco in the summer, the air temperature is the same as at the Sierra pass -Nevada at an altitude of 2140 m. 22 km northwest of San Francisco at an altitude of 730 m in summer it is 4 °C warmer than below, due to the presence of a stable monsoon-type temperature inversion.

Dictionary of winds. - Leningrad: Gidrometeoizdat. L.Z. Shit. 1983.

See what "SUMMER MONSOON" is in other dictionaries:

Monsoon off the northeastern coast of Africa. See Tropical Monsoons...Wind Dictionary

Monsoon- This term has other meanings, see Monsoon (meanings). Monsoon (from Arabic “موسم” (mysem), season) steady winds that periodically change their direction; in summer they blow from the ocean, in winter from land; characteristic of tropical regions ... Wikipedia

- (from Arabic, Mausim season) large-scale air flow with a corresponding weather complex. Seasonal wind that occurs at the border of the sea and the continent as a result of their unequal heating and changes its direction twice a year by ... ... Wind Dictionary

Refers to extratropical. Winter M. is caused by strong cooling of continental air under anticyclonic conditions. In the Amur Region and Khabarovsk Territory in winter, the air temperature drops to 40 ° C under clear skies, frosts persist ... Wind Dictionary

MONSOON- Origin: from Arab, Mausim season - a stable system of winds operating between land and ocean and changing direction by 120-180° twice a year. The main reason for M. is seasonal temperature contrasts between the ocean surface and adjacent... ... Marine encyclopedic reference book

Cold autumn winds from mountain coasts towards unfrozen lakes (Sarma, Kultuk, Barguzin, etc.). Before freeze-up, the temperature differences between the surface of the lake and the shores reach 40 ° C, which is the reason for the monsoon intensification of the coastal ... ... Wind Dictionary

Summer oceanic tropical monsoon in the northern Indian Ocean. See Tropical Monsoon...Wind Dictionary