Global Climates

Global Distribution Of Climate

• Climate describes the temperature, precipitation, and other weather conditions of a certain area.

• The climate of an area describes how these variables may be over a long period, for instance the South of France in the summer is hot and dry.

• However this is not always the case as there are some days when it is raining and fairly cool.

• These daily changes do not affect the overall climate of the area, and are described as the weather of the area for that day.

World Climates

Factors Affecting Climate

• Altitude• Aspect• Distance From The Sea• Latitude• Ocean Currents• Prevailing Winds

Altitude

• Temperature falls the higher you are. • The loss in temperature is approximately 10°C for

every kilometre you rise. • This fall in temperature with height is due to the

fact that the air at higher altitudes is thinner. • There are fewer molecules available to receive

and retain heat. • Wind chill may also mean that the temperatures

in upland areas are lower than expected.

Aspect

• This relates to the direction in which a place is facing.

• Aspect only really affects local climate, not global ones.

• In the Northern Hemisphere, south facing slopes receive far more sunlight than north facing ones.

• These are therefore much better for agriculture and often settlement will locate there due to the better aspect.

Distance From The Sea

• The sea can have a great influence over climates in maritime regions.

• The sea takes much longer to heat up but retains that heat far better than the land.

• Consequently the land is often warmer than the sea during the day, however the situation is reversed at night.

• This means that places like Britain, which are near the sea, have relatively cool days and warm nights, as well as warm summers and mild winters.

• The influence of the sea diminishes as you move further inland, for instance to central Europe, where warmer winters and cooler summers will be experienced.

Latitude

• Latitude on global climates. • Lines of Latitude are those that run

horizontally around the world. • The most famous line of latitude is the

Equator. • Using the lines of latitude we can easily divide

the world in to specific climatic sections.

Latitude

• Between 23.5 South and 23.5 North is the region called the tropics.

• These receive the most heat from the sun because it is almost directly overhead and so the solar radiation does not have to travel through very much of the atmosphere.

• It heats a very concentrated area of the surface of the ground.

• Between 23.5 and 66.5 in both the Northern and Southern Hemispheres are the temperate regions.

• These have reasonably hot summers and mild winters.

Latitude

• Above 66.5 in both hemispheres are the Polar Regions, which are very cold.

• They receive sunlight for only half the year due to the angle of the Earth on its rotation.

• During the months when they do have sunlight, it travels to them at a very shallow angle, meaning that it has to travel through a lot of the atmosphere and has to heat a wide area of the surface.

Ocean Currents

• Many areas beside the sea are affected by ocean currents.

• These can be either warm or cold currents. • The United Kingdom is directly in the path of

the Gulf Stream and the Northern Atlantic Stream, which bring warm water from the Caribbean across the Atlantic to our shores.

• This current alone is the reason why our climate is mild compared to places of similar latitude like Newfoundland.

Prevailing Winds

• The prevailing (most common) wind in the United Kingdom comes form the South West.

• If a prevailing wind travels over a warm surface it will bring warm weather, whilst if it travels over a cold surface it will bring cold weather.

• The south-westerly winds in Britain travel across the Atlantic.

• In the summer this means that the air is cooled, whilst in the winter the water warms the air, bringing warmer winters than we might expect.