AIR MOVEMENT PART 2- AIR MASSES

Air masses

An air is an extremely large volume of air that has similar temperature, pressure and moisture properties throughout.

Formation of Air masses

An air mass is formed over both land and water surfaces. The area (land or water) must be stable and calm. When air remains over land or water for a long time, the air picks up the climatic condition of the area such that when the area is cold, the air mass becomes cold and when the area is hot, the air mass becomes hot.

Types of air masses

Polar = cold                 tropical = warm                      maritime = water        continental = land or dry

There are four major types of air mass

1.  Polar maritime (Pm) : they are cold and moist

2.  Polar Continental (Pc) :  they are cold and dry

3.  Tropical maritime (Tc) :  they are warm and moist

4.  Tropical continental (Tc) : they are warm and dry e.g harmattan winds

 

Weather fronts

A weather front is a boundary separating different air masses.  These different air masses should have different air densities, humidity, and temperatures. 

E.g cold and warm air mass

Effects of moving air masses

1. Air masses transport pollutants such as CFCs, SO₂, NO₂.

2.  Air masses destroys the Ozone layer

3. Destruction of landscape

4.  Flood

5. Pollution: Moving air masses sweep out everything in their path including pollutants. 

6. Temperature regulation

Global winds

Wind is the movement of air caused by the uneven heating of the Earth by the sun. Warm air rises for cold air to replace it which creates convectional current.

Types of Winds

1. Westerlies:  These are winds that moves from the equator to the poles but because of the rotation of the earth they appear to be moving from west to east. They are warm and have low densities

2.  Easterlies or trade winds :  These are winds that moves from the poles to the equator but because of the rotation of the earth they appear to be moving from east to west. They are cold and denser. eg harmattan winds that blows from the Sahara desert.

Storms

A storm is a disturbance in the atmosphere that has noticeable effects on earth’s surface. It is usually characterized by heavy rains, strong winds, thunder and lightning.

There are different kinds of storm yet they possess common characteristics.

NOTE: Tornadoes, hurricanes, typhoons are terms which describes cyclones in different part of the world.

Cyclone

A cyclone is a meteorological term for a storm system characterized by low pressure center and thunderstorms that produce strong winds and flooding rains. Cyclones develop over warm seas near the equator. Air heated by the sun rises quickly which creates areas of low pressure. As the warm air rises it condenses into massive clouds. Cool air rushes to fill the empty space left behind by the warm air, but of earth’s rotation the cool air bend inwards to for a cone. The swirling air rotates faster and faster, forming a huge circle with a cloudless center called eye where there is no rain. Cyclones feed on the heat released when moist air rise and condenses.

Warning signs of approaching storms

1. strong winds

2. rising sea levels

3.  dark clouds

4.Blowing debris

  

PRECAUTIONS AGAINST THE EFFECTS OF STORMS

1. Always listen out to weather forecasts and reports on radio or television.

2. Move to a safer areas if a storm is forecast to strike in your area

3. Since storms could cause closure of stores and food joints, store enough food with you.

4. Keep emergency phone numbers handy.

5. Stay away from the sea and coastal area.

6. After the storm, makes sure everything is in order and safe. Check gas leakages and other appliances especially electronic appliances before using them; make sure they are well dry.