Factors Affecting Air Pressure:

“In a high pressure system you have dense air subsiding downwards and pushing down at the surface, Because the surface air is being pushed down from the air above it spreads outwards, which is why we generally have fair weather [in mid-latitude regions] when we have high pressure systems”.

Air near the center of a High Pressure System moves outward towards areas of low pressure. CLOCK-WISE – In the northern hemisphere the air in a high pressure system moves in a clockwise direction.

• Temperature: As the temperature increases, air expands because of which its density decreases which results in low pressure.
• Height from Sea Level:
• Moisture in Air (Humidity):
• Gravitation of Earth:
• Rotation of Earth:

Atmospheric pressure decreases as the height of a surface above ground level increases. This is because, as the altitude increases: the number of air molecules decreases.

Water is not a suitable barometric liquid because: (i) The density of water is low (103 kg m-3). Water barometer will support 10.4m of water at sea level. It is impractical to have such a long tube.

That pressure is called atmospheric pressure, or air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to Earth. Atmospheric pressure is commonly measured with a barometer. In a barometer, a column of mercury in a glass tube rises or falls as the weight of the atmosphere changes.

In the free atmosphere, the air’s density decreases as the air is heated. Pressure has the opposite effect on air density. Increasing the pressure increases the density. Weather systems that bring higher or lower air pressure also affect the air’s density, but not nearly as much as altitude.

Air temperature changes the air pressure. For example, as the air warms up on a hot summer day, the molecules in the air become more active and they use up more individual space even though there is the same number of molecules. This causes an increase in the air pressure.

The correlation between barometric pressure and wind velocity is that as pressure increase wind velocity decreases.

You’ll usually hear forecasters give measurements in either inches of mercury or in millibars (mb). Forecasters use changes in air pressure measured with barometers to predict short-term changes in the weather. We call this flow of air molecules wind.

Answer: When wind speed increases, air particles are moving away from a particular place, and hence the air pressure decreases. If the speed of the wind increases…..the pressure decreases and if the speed decreases the pressure increases.

Areas of high and low pressure are caused by ascending and descending air. As air warms it ascends, leading to low pressure at the surface. As air cools it descends, leading to high pressure at the surface.

Air Pressure and Winds Warm air rises, creating a low pressure zone; cool air sinks, creating a high pressure zone. Air that moves horizontally between high and low pressure zones makes wind.

A barometer reading of 30 inches (Hg) is considered normal. Strong high pressure could register as high as 30.70 inches, whereas low pressure associated with a hurricane can dip below 27.30 inches (Hurricane Andrew had a measured surface pressure of 27.23 just before its landfall in Miami Dade County).

1083.8mb