Factors influencing weather In Zambia

There are different factors influencing weather in different parts of the world, and therefore also cause the climate to be different in different parts of the world. These factors include seasons, latitudes, altitudes and prevailing winds from the sea.

Seasons

To understand seasons, we need to understand that the earth moves in two ways:

• The spins or rotates on its axis (an imaginary line down its centre), like soccer player spinning a ball on his or her fingertip.
• This rotation of the earth cause day and night.
• While the earth is rotating on its axis, it also revolves or moves in a fixed path called an orbit around the sun.
• One revolution of the earth around the sun takes 3651/4 days.
• The earth’s is title at 231/2 degrees. This tilt is why we have seasons.
• When the axis points towards the sun, it is summer for that hemisphere.
• When the axis points away from the sun, that hemisphere will have winter.

Altitude

• Altitude refers to how high or low a place is above sea level.
• Generally places at a higher altitude are cooler than places at a low altitude.
• When we look at the climate of Zambia in the next section, we will see how the effects of altitude and latitude (discuss on the next page) together affect the temperatures in different parts of the country.

Latitude

Latitude refers to how far north or south of the equator a specific place is. Since the earth is round and not flat, the sun’s rays fall unevenly on the land and oceans on different parts of the earth:

• The sun’s rays are direct near the equator.
• It is hotter closer to the equator.
• The polar region at the top and bottom of the globe, however, at such an angle to sun that they get little or no sunlight during the winter, causing much colder temperatures.

Prevailing winds and distances from the sea

Global air movements

• The differences in temperature between parts of the world at different latitudes create a movement of air and water in great swirling currents.
• These movements distribute heat energy from the sun across the planet.
• When air in one region is warmer than the surrounding air, it becomes less dense and begins to rise, drawing in more air underneath. Cooler, denser air sinks, pushing air outward to flow along the surface and complete the cycle.
• These movements of air create winds that blow from a certain direction at certain times of the year for different places.
• We refer to these typical wind patterns as the prevailing winds for a certain area.

Ocean currents

• Ocean currents also distribute heat energy around the planet.
• The position and distance from the sea of a certain place also therefore affect its weather.
• For example, temperature of places along the coast is affected by ocean currents.
• Along the east coast of southern Africa, there are the warm agulhas and Mozambique currents.
• On the west coast of southern Africa, there is a cold current called the Benguela current.
• Temperatures along the east coast of Africa are therefore higher than along the west coast.
• When winds blow in from the sea, they contain more moisture than winds that blow fro, inland areas.
• The distance and position of a place relative to the sea will therefore also affect its rainfall.