Air masses constantly circulate in the atmosphere. Their names correspond to the place on the map where they were formed. Air masses are continental (formed over land) and sea (formed over the water surface). They exert pressure on the surface of the earth and on all creatures that inhabit it. This effect has different strengths. The area of reduced pressure in the atmosphere is a storm or cyclone. However, this applies to measurements on the surface, correlated with sea level. In the mountains, the area of low pressure is characterized by the normal state of the atmosphere. This is a common occurrence here.
Atmosphere pressure
The area of reduced pressure in the atmosphere is a relative indicator.
It should be considered as a parameter measured above sea level. In this case, 765 mm Hg is considered normal. The greater the height of the measurements, the lower the forming atmospheric pressure areas. At the border of snow caps in the mountains, this indicator is considered normal at a value of 350 mmHg.
Due to this, the concept of areas of low atmospheric pressure is considered from the point of view of the indicator and the surrounding air masses. For each area where they were formed, determine the characteristic features that affect the circulation. The definition of weather in a particular region always correlates with studies of all the natural phenomena that arise in the region.
Air circulation
The formation of areas of low atmospheric air pressure is associated with the process of its circulation.
It occurs due to the inclination of the Earth’s axis and the heterogeneity of the planet’s heating at the equator and poles.
The region of low atmospheric air pressure is formed due to high temperatures at the equator. When heated, it expands and rises. And given the fact that the opposite effect occurs at the poles and increased pressure occurs, air masses circulate.
Moreover, if low pressure forms in one area, then increased pressure will necessarily form in another.
Cyclone Definition
The area of reduced pressure in the atmosphere is a cyclone. It manifests itself in the form of a storm or even a tornado. In the center of the cyclone, the pressure is much lower than at the edges.
If it formed in the northern hemisphere, the movement of air masses will occur counterclockwise. On the south side of the planet - vice versa. The Coriolis force moves the cyclone to the right, and in the south - to the left.
The area of low atmospheric pressure, where a tornado or storm forms, is initially located above the water surface. Therefore, this natural phenomenon brings with it rainy, cloudy weather. Frequent gusts of wind are caused by pressure differences in the center and periphery of the cyclone. An area of low atmospheric air pressure is formed with summer rains and cooling, and in winter with thaws and snowfalls. In this case, air moves from the edge of the cyclone to its center, where it rises and cools.
Education mechanism
The cyclone vortex is called the “snake ring”. Its diameter sometimes reaches several thousand kilometers.
An area of reduced air pressure is formed in temperate latitudes. This occurs when warm moist air currents collide from the equator with cold dry air flows from the poles. Between these opposites there is a border called the front. Cold air pushes the warm layer a little. Its masses collide. The ellipsoidal movement begins. Capturing nearby air layers, the cyclone moves at a speed of up to 50 km / h. The periphery rotates faster than the center. Depending on the location of occurrence, sometimes very strong storms occur. They bring destruction at times of unimaginable proportions. The area of low pressure in the atmosphere is a tornado. At its center there is a lack of air. Cold winds make up for it. Warm air currents are forced up, cools, and moisture condenses in the form of precipitation. The life expectancy of a storm is different and depends on the geography of the area.
Tropical whirlwind
Vortices of tropical latitudes are much stronger than cyclones formed in temperate latitudes.
In the region of 5-20 degrees south and north latitude above the ocean surface, similar natural phenomena occur. Where an area of low atmospheric pressure is formed, the movement of air masses occurs. However, in tropical cyclones it is sometimes very large. Reaches 10-30 m / s. Its center is called the "eye of the storm." The weather is quiet here. The wider it is, the more destructive the storm is. Usually the “eye of the storm” is 30 km, but sometimes it reaches 70 km. Global warming leads to an increase in the power of cyclones of tropical latitudes. Of course, there are also insignificant similar weather phenomena. However, powerful storms and hurricanes sometimes reach European countries, America, where they leave enormous destruction with numerous casualties.
Types of cyclones
The area of low atmospheric air pressure is of varying strength. There are 4 types of cyclones:
- The disturbance, which is characterized by the movement of air with a speed of not more than 17 m / s.
- Depression - the speed is in the range of 17-20 m / s.
- I call a storm a cyclone, the center of which moves up to 38 m / s.
- If the movement of the “eye of the storm” exceeds 39 m / s, it is already a hurricane.
This is a common classification. Nature sometimes throws up “surprises” to mankind in the form of storms unforeseen in strength in the uncharacteristic latitudes. For example, in 1999 the powerful hurricane Lothar shook Europe’s trap. Meteorologists could not have foreseen it, since its monstrous power led to the off-scale sensors. Some of them didn't even work.
More than 70 people died due to the raging elements.
