Atmospheric general circulation: what is and how it occurs

Atmospheric general circulation is the Large -scale air -scale movement in the Earth’s atmospheremainly driven by the solar energy. This movement occurs due to the differences in temperature and pressure between different regions of the planet, which generates Wind patterns that allow heat transport from the warmer areas (near Ecuador) to the coldest areas (near the poles). The general circulation system is composed of a series of cells that are repeated in each hemisphere. These are the Hadley, Ferrel and Polar cells.

In this other post you can know the composition of the atmosphere.

Atmospheric general circulation occurs as a result of temperature differences between different regions of the planet, which generates variations in atmospheric pressure. This process follows a series of stages:

1. Solar radiation and unequal heating: Solar radiation does not reach the entire surface of the earth evenly due to its spherical shape. This causes a thermal gradient, that is, a difference in temperature between Ecuador (warmer) and poles (colder).
2. Convection in the atmosphere: The air in areas near Ecuador is heated more quickly and, when heating, becomes less dense and rises, creating a low pressure region on the surface. As this air rises, cools and moves towards higher latitudes. Cold air, denser, in regions near the poles tends to descend, creating high pressure areas.
3. Circulation cell formation: This rise and descent of air generates circulation patterns in the atmosphere known as cells.

Atmospheric circulation Determine the predominant wind patterns throughout the planet, which significantly influence the weather and time in different regions. The winds occur because the air tends to move from high pressure areas in the direction of low pressure areas, seeking to balance differences in the atmosphere.

The general circulation of the atmosphere creates several predominant winds that follow global patterns. These winds vary according to latitude and are grouped into three main types associated with the three atmospheric circulation cells:

• Alisios winds (Hadley cell): Alisios winds are air currents that blow from subtropical latitudes (around 30 ° N and 30 ° S) to Ecuador. They are produced by the descending movement of air in these latitudes, which generates high pressure areas. Here we tell you more about the winds: what they are and how they form.
• Western winds (Ferrel cell): They are currents that blow from average latitudes (around 30 ° to 60 ° N and S) to the east. These winds are driven by the descending air of the railroad cell, which is between Hadley and Polar cells.
• Polar winds (polar cell): In these regions, cold and dense air descends, creating high pressure areas in the poles. As this air moves towards lower latitudes, the Coriolis effect diverts it to the west, forming the polar winds of the east.

Atmospheric cells are large air circulation systems that are part of the structure of atmospheric general circulation. Are the following:

• Hadley cell: Hadley’s cell is responsible for atmospheric circulation in the tropics, moving heat towards middle latitudes, and plays a key role in tropical climatic patterns, such as seasonal rains.
• Ferrel cell: The hardware cell works as a link between the Hadley cell and the polar cell, redistributing heat and energy from subtropical latitudes to the poles. It is the reason behind the patterns of variable time in temperate regions, such as frequent storms and seasonal variations.
• Polar cell: The polar cell regulates the transport of cold air to the average latitudes, influencing the climate patterns in the polar regions and contributing to the formation of storm systems in the average latitudes.

The Coriolis effect is a apparent force that is generated due to the rotation of the Earthand has a direct impact on atmospheric general circulation, especially in the way in which winds and ocean currents move. It is key to understand why winds do not move straight from high pressure areas in the direction of low pressure areas, but They deviate to one side or another depending on the hemisphere in which they are.

As the air moves in the atmosphere, the rotation of the Earth deviates its movement, creating the predominant winds that we see in the different areas of the planet.

In the Hadley cellhot air rises in the equatorial zone and moves towards subtropical latitudes, where it descends. Once the air descends in these high pressure areas (around 30 ° latitude), it begins to move back to Ecuador as Alisios winds.

In the Ferrel cellthe air moves from subtropical latitudes to middle latitudes (around 60 °). Due to the Coriolis effect, this moving air is diverted in the direction opposite to the winds.

In the Polar cellcold air descends in the poles and moves towards the lowest latitudes. As the air moves to Ecuador, the Coriolis effect diverts these winds:

• In it Northern Hemispherepolar winds are diverted to the right, blowing from this to west.
• In it South Hemispherepolar winds deviate to the left, also blowing from this to west.

These polar winds of the East play a role in the maintenance of extremely cold weather in the polar areas, while interacting with the west winds in the middle latitudes, generating polar fronts and storms.

In this other article we explain more about the Coriolis effect: what it is, what it consists of and examples.

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