Climate Characteristics (Cambridge (CIE) IGCSE Geography)
Revision Note
Written by: Bridgette Barrett
Reviewed by: Jenna Quinn
Equatorial Climate Characteristics
World climate distribution
Climates vary across the world
The reasons for these climate types include:
Latitude
With distance from the equator temperatures and sunshine hours decrease as the solar radiation is more dispersed at the poles and it has to pass through a greater amount of atmosphere
Altitude
Increases in altitude lead to decreases in temperature
Continentality
Locations further inland heat up more quickly in the summer and cool more quickly in the winter
Ocean currents
Warm and cold currents circulate in the oceans either warming or cooling the adjacent land
Aspect
In the northern hemisphere slopes facing south are warmer
Prevailing winds
Winds coming from warmer areas bring warmer air, increasing temperatures
Pressure systems
Areas usually affected by low pressure such as the equator have rising air, condensation, and cloud formation leading to more precipitation
Areas affected by high pressure have dry conditions due to the sinking air
Equatorial climate distribution
Equatorial climate characteristics
Location
Low latitudes
Within the Tropics 23.5° north and south of the equator
Amazon in South America, New Guinea, South-east Asia, Zaire Basin
Annual precipitation
Over 2000mm
Temperature range
Low range of mean monthly temperatures - 26-28°C
Constant high temperatures
Diurnal range is about 7oC
Seasons
No seasons - hot and wet all year round
Humidity
High, usually over 75-80%
Prevailing winds
Winds blow into the equatorial region from high-pressure areas to the north and south.
The winds from the north blow from the north-east and the winds from the south blow from the south-east.
The winds are known as the trade winds
Factors influencing the equatorial climate
There are a range of factors that influence the climate including:
The midday sun is almost directly overhead all year meaning there is maximum insolation
Low pressure all year leads to rising air, condensation, cloud formation, and high precipitation levels
Dense vegetation cover leads to high levels of evaporation and transpiration
The warm air stores large amounts of water vapour until the temperatures start to cool in the late afternoon which then leads to heavy, daily convectional rainfall
Hot Desert Climate Characteristics
Hot desert climate distribution
Hot desert climate characteristics
Location
15° - 30° north and south of the equator (tropical and sub-tropical)
North Africa - Sahara, Southern Africa - Kalahari and Namib, Australia. Middle East
Annual precipitation
Below 250mm
Temperature range
Daytime temperatures can reach 50°C but average around 25°C
Night-time temperatures below 0°C
The diurnal range is large up to 45°C
The annual range is around 15°C
Seasons
Summer and winter
Humidity
Low often between 10-30%
Prevailing winds
The winds are offshore blowing from the east across the land, so they do not collect any moisture
Factors influencing the hot desert climate
High pressure all year means the air is descending and warming
Precipitation does not occur because the air is not rising
Prevailing winds are often from over land masses which means they contain little moisture
Some deserts are in a rain shadow so there is little rainfall
Cold ocean currents on the west side of continents may reduce summer temperatures due to the cooling effect of the ocean
Influence of pressure systems
Hot deserts form between 15o- 30o north and south of the equator as a result of the atmospheric pressure systems
Air rises at the equator and when it reaches the upper atmosphere it moves north and south
The air cools and starts to sink
This creates a zone of high pressure at about 30o north and south of the equator
Due to the sinking air, warm air cannot rise, condense, and form clouds. This results in high aridity
Worked Example
Explain how high atmospheric pressure influences the climate of hot deserts.
[3 Marks]
Answer
Air is descending [1]
It heats up/does not cool [1]
Condensation does not occur/clouds do not form [1]
Precipitation is low/does not occur/drier/only has e.g. 250 mm per annum etc [1]
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