Air pressure and stuff

What is air/atmospheric pressure? How is it measured?

The downward force exerted by air on the Earth’s surface. It is measured in millibars (mb) using a barometer.

What is the relationship between air pressure and altitude?

The higher the altitude, the lower the pressure as air molecules are far packed and air becomes thinner. 

The lower the altitude, the higher the pressure as air molecules are closely packed, and air becomes denser. 

THE LAWS OF AIR PRESSURE/WIND:

1. Hot air rises → low concentration and pressure

2. Cold air sinks → high concentration and pressure

3. Air pressure moves from high to low pressure area

4. Air pressure keeps moving until it reaches an equilibrium

The Corolis Effect

• Between the months of June to September, it is summer in the Northern hemisphere and winter in the Southern hemisphere. 

• During this period, air over Central Asia heats up, expands and rises, creating a low pressure area while the cold, dense air over Australia sinks and creates a high pressure area. 

• As air moves from an area of high pressure to an area of low pressure, air moves from Australia as the Southwest monsoon winds towards the Indian sub-continent and Central Asia. 

• As the wind crosses the equator, the Coriolis Effect deflects it to the right. These wind then become the Southwest monsoon winds and pick up moisture as they move across the Indian Ocean towards Central Asia. 

• The warm moist air from the Indian Ocean, Arabian Sea and Bay of Bengal brings rain each year to parts of South Asia between June to September. 

What is wind?

Wind is moving air created when neighbouring locations have different air pressures.

What is the significance of local winds?

They help to regulate temperature, lowering the temperature range.

Explain the formation of sea breeze. (Day)

A sea breeze is wind that blows from the sea to the land. During the day, the land heats up faster than the sea. The warm air over the land rises. As a result, the air pressure over the land is lower than the sea. The area over the sea is a high pressure area. Therefore, wind blows from the sea to the land during the day to form a sea breeze because air moves from a n area of high pressure to an area of low pressure.

Explain the formation of land breeze. (Night)

A land breeze is wind that blows from the land to the sea. At night, the sea loses heat slower than the land. The warm air over the sea rises. As a result, the air pressure over the sea is lower than the land. The area over the land is a high pressure area. Therefore, wind blows from the land to the sea at night to form a land breeze, because air moves from an area of high pressure to an area of low pressure.