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Present all the items related to atmospheric pressure.

Present all the items related to atmospheric pressure.

Write below all the items related to atmospheric pressure.

Atmospheric pressureatmospheric pressureAtmospheric pressure is where a body of air causes pressure on a cetain part of the Earth's surface. It can be logically stated that atmospheric pressure is lower in the mountains and higher at sea level. This is indeed the case.

The level of atmospheric pressure varies, not only depending on height above sea level. At various parts of the globe, located near the surface of the Earth, different pressure levels can be found. In these locations, where the pressure is higher than in surrounding areas, we are speaking about high atmospheric (barometric) pressure. On the other hand, where the pressure is lower than in surrounding areas, we are speaking about low atmospheric (barometric) pressure. The difference in pressure causes air to move from high to low. Wind is caused by horizontal or near horizontal air movement, resulting from the difference in pressure.

If not for the phenomenon known as the Coriolis force (see: Earth's rotationixr5Y2Lxy7Earth's rotation, question 3. Consequences of rotation), winds would blow radially from high pressure areas to low. However, the Coriolis force causes the wind to turn (to the right in the northern hemisphere and to the left in the southern hemisphere) and away from centres of high pressure. It also moves clockwise (in the northern hemisphere) and anti‑clockwise (in the southern hemisphere). This is different to low pressure systems, which are masses of air where the pressure is lower than that surrounding them. The wind blows towards the centre of the low, but because of the Coriolis force it starts to turn and blow in a counter‑clockwise direction (in the northern hemisphere) or clockwise (in the southern hemisphere). Low pressure systems where winds blow spirally (due to the Coriolis force) towards their centres, are known as cyclones cyclonescyclonecyclones, and high pressure systems with spiral winds blowing outside are anticyclones – anticyclonesanticycloneanticyclones.

The dynamics and movement of barometric pressure systems can be shown on climatic maps. To do this, pressure is measured in many locations, and then places with the same reading are connected. The lines created in this way are called isobars.

Vertical, or near‑vertical movements of air in the atmosphere, which come about as a result of heat near the surface of the earth, we call thermal convection. Convection is the movement of air upwards (warm air rises) and downwards (cold air falls). Although these are movements of air, we do not refer to them as winds.

In the northern hemisphere the winds blow from the barium upwardly in a clockwise direction, and towards the lowlands contrary to their movement. On the other hand, in the southern hemisphere the winds blow from the barium bump anticlockwise, and towards the low tide according to it.

Summary

• Atmospheric pressure varies according to altitude.

• Wind is the horizontal movement of air from high to low pressure areas.

• The Coriolis force changes the direction of winds blowing on the Earth. In the northern hemisphere, winds from the centre of high pressure systems blow in a clockwise direction, and in the southern hemisphere they blow anti‑clockwise. On the other hand, winds coming from the centre of low‑pressure systems in the northern hemisphere blow anti‑clockwise, and clockwise in the southern hemisphere.

• Winds blow everywhere on the Earth. They change on a yearly or daily basis, or can be localised.

Keywords

pressure, wind, isobars, cyclones, anticyclone

Glossary