trade winds introduced
trade winds (also known as trade winds) refers to the low altitude wind blowing from the subtropical zone equatorial low pressure zone.
trade winds (Tradewind) on both sides of the equator in the lower atmosphere, the northern hemisphere from the north east, southeast wind blowing in the southern hemisphere, the wind direction changes little, so that they every year, appeared stable, very disloyal this is the reason tradewind translated "trade winds" in Chinese is. Trade winds generally distributed in the vicinity of the north and south latitude 5 ° ~ 25 °, and is limited to the lower troposphere, an average thickness of about 4000 m. As the trade winds are blowing toward lower latitudes, high-temperature zone, so there is no condensation conditions, drying properties. Some of the world's desert and semi-desert, are located in the trade winds. Ancient Chinese literature in the "trade winds" is the word, means "to make changes at any time, on a regular basis from the orientation of the wind, that the monsoon." Check the "source" "trade winds" strip can see this explanation and citations. So, can the word generally refers to the trade winds, it can be here as the modern meteorology refers specifically tradewind meaning.
Category
According to the trade winds and the southeast trade wind direction is divided into the northeast trade winds, is the northeast trade winds in the Northern Hemisphere, the Southern Hemisphere southeast trade winds.
Cause
formed trade winds about the earth three times circulation, long-term exposure to the sun, heat up to the equator, equatorial rising heated air near the ground, forming a low pressure zone near the equatorial surface , a relatively high pressure at high altitude, altitude high pressure moves to either side in the direction of low pressure high, due to the influence of the Coriolis force, deflected in the vicinity of 30 degrees latitude north and south parallel with the isobars, where atmospheric accumulation, forced to sink, forming a subtropical high pressure belt near the ground. At this time, the pressure difference is generated between the equatorial low pressure zone and the subtropical high pressure zone, the air flow from the "subtropical high pressure zone" flow "red low."
in the influence of the transfer bias, the air in the south in the northern hemisphere subtropical runtime deflected to the right to run the air pressure gradient force formed northeast, i.e. northeast trade winds. Conversely southern hemisphere formed southeast trade winds. In the upper troposphere and the trade winds prevailing wind direction opposite, i.e., anti-trade winds. And anti-trade winds trade winds constituting a closed vertical circulation between the equator latitude South 20 ~ 35 °, i.e. Hadley circulation.
Because of the subtropical high was especially evident in the ocean, there is year-round, there is only winter on the mainland. So prevalent in the tropical ocean and stable year-round trade winds, trade winds poor stability on the continent, and only occurs in the winter months. Two hemispheres confluence trade winds near the equator, is formed ITCZ. Trade winds is a very stable system, but there are significant interannual variability. Some people think that the collapse of the eastern Pacific trade winds, equatorial sea surface temperature may affect the intense rise, El Nino is the cause of formation. Its enhancement, weakening El Nino is a regular. Trade winds greatly diminished, resulting in the equatorial region of the zonal circulation WACKER also weakened. When the anti-El Niño, trade winds strengthened to enhance circulation and westward expansion Wacker.
period
on the hemispheres with trade winds will change with the seasons and North-South movement occurs regularly. Such as the northeast trade winds on the northern Pacific Ocean, in March each year at latitude 5 ° ~ 25 °. To September, with the entire air moving north to latitude 10 ° ~ 30 °, the second to March, the entire air belt back to the vicinity of latitude and 5 ° ~ 25 °. Thus, in a particular area trade winds movable range, there will be trade winds periodically changing phenomenon.
constant trade winds will warm moist air of the ocean taken land, the more moderate the local climate, such as rainfall and humid climate in the second half of subtropical moisture from the trade winds that is brought; Central America, the Caribbean Zhu the eastern island of rainfall often than the west, but also because of the influence of the trade winds. Because of the strong equatorial regions the sun, hot all year round, resulting in strong updrafts, the formation of low pressure, air flow to the high altitude after the poles began to spread. When the air flow to the north and south latitude 30 degrees, began to encounter subtropical subsidence, when the air is quite dry, because moisture loss as the rain near the equator. Since the low pressure gas is flowing from the high pressure, high pressure gas stream will be settled with the air flow back in the equatorial region, are formed in the north in the northern hemisphere, in the Southern Hemisphere southerly formed, but affected by the Coriolis force, air is blown to the west, it the situation will cause the northern hemisphere from the north east, south east of the southern hemisphere (the wind is blowing from the northeast and south-east).
moving range
is the wind blowing the low-pressure zone from the high pressure zone, is the trade winds close to the ground for a wind blowing from a low pressure zone equatorial latitudes subtropical 30 °. This wind timed appear in a fixed area, and wind direction change, very trustworthy, so people give it a good name - trade winds.
Earth's rotation due to the Coriolis force is formed so that the total air movement to the right side in the northern hemisphere, in the Southern Hemisphere partial left, therefore, trade winds wind hemispheres very inconsistent. In the northern hemisphere, the wind blowing from the northeast to southwest, "the northeast trade winds"; in the southern hemisphere, the wind blowing from the southeast to the northwest, "the southeast trade winds." Magellan Pacific fleet when it is encountered by the "Southeast trade winds" and then enter the "doldrums" and the final completion of this great initiative.
Precipitation impact
areas affected by the trade winds, and some less precipitation, and some more precipitation, which is related to factors which the land-sea location and terrain status. First, the areas affected by major trade winds on Earth.
On Earth, located in areas with trade winds mainly Asia and Europe West Asia, North and South Africa, in the eastern part of the continent of South America, North America, Mexico, Australia and north-central plateau region. A second distribution position trade wind drier area.
First, in North Africa and West Asia, the northeast trade winds, where the trade winds blowing from the arid inland area, small humidity, precipitation is very small.
Second, mainland southern and southeastern Africa by the South American continent southeast trade winds, the trade winds blowing from the ocean here are, but by blocking effects of high altitude terrain, moist air over the ocean is difficult to reach, precipitation also scarce. Also in North America, Mexico plateau as well.
Third, west of the Great Dividing the Australian continent, leeward slope located in the southeast trade winds, rain shadow area, precipitation is particularly low. Third, the distribution of the position of the trade winds and rainy region.
trade winds can not bring a lot of rain in coastal areas or along the windward slopes of some of the mountain plateau edge, the trade winds tend to bring a lot of rain. As the southeast coast of Brazil Plateau, the eastern side of the island of Madagascar, Australia's northeastern coast, southeast trade winds terrain elevation rain in the mountainous terrain formed windward slope, abundant rainfall, coupled with the lower latitudes have been in these areas, so that these districts have formed a tropical rainforest climate.
trade winds
by the subtropical high pressure belt directional wind blowing trade winds in the equatorial region called. In the Coriolis force, wind direction deviation occurs in the northern hemisphere is formed northeast trade winds, southern hemisphere formed southeast trade winds. Year-round trade winds blowing in the area, called the trade winds.