Transcript Global Climates - Geog

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.