The IEB Grade 11 Climatology notes cover a comprehensive range of topics in geography, including weather patterns, global air circulation, and their influences on different climates. The thorough coverage of topics such as temperature, wind, air pressure, and global atmospheric movements, coupled w...
Weather - the daily conditions / state of the atmosphere.
Climate - average weather conditions over 30+ years.
The four elements of weather & the instruments used:
Temperature - thermometer Wind speed - anemometer
Humidity - hygrometer Air pressure - barometer
The Earth’s atmosphere is made up of solids, liquids & gases.
Layers of the atmosphere:
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
Temperature decreases in the troposphere before it increases in the stratosphere.
Water vapour provides moisture in the atmosphere. Water vapour & CO2 trap heat & keep
Earth warm.
Energy from the sun is transferred through space & through the earth’s atmosphere to the
Earth’s surface.
The sea moderates the temperature.
Clouds prevent sun from reaching Earth’s surface keeping it cool. They also trap terrestrial
radiation underneath keeping it warm.
The earth’s energy balance
Earth is heated by incoming solar radiation or insolation. The earth then transfers this
heat energy into the atmosphere by terrestrial. The amount of heat energy in the
atmosphere therefore depends on the amount of insolation. But insolation is not equal all
over the earths surface.
• amount of insolation depends on 2 factors - latitude & seasons.
• atmosphere is heated more at the equator than at the poles.
• atmosphere is heated more during summer than winter.
,Latitude
Refers to the position north & south of the equator. Equator is much warmer than the poles.
Sun strikes the surface at a low angle & heat is spread over a large
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Sun is directly overhead all year round & heat is concentrated.
Earth
Sun strikes the surface at a low angle & heat is spread over a large area -
atmosphere temp isn’t very high.
• The sun’s rays are more direct at the equator & less direct at places further from the
equator.
• Same amount of energy is available to heat a smaller surface of Earth & its atmosphere
at the equator than at places further from the equator.
• At poles, same amount of energy has to heat a larger surface area & a larger amount of
atmosphere.
• Places closer to the equator are therefore hotter than places further from the equator.
Heat zones based on latitude
90° N
North Pole polar zone
Arctic Circle 66,5°N ·
subpolar zone
temperature zone
subtropical zone
Tropic of Cancer 23,5°N
tropical
equator 0°
zone
Tropic of Capricorn 23,5°S
subtropical zone
temperature zone
Antarctic Circle 66.5°S subpolar zone
South Pole polar zone
90° S
Earth’s rotation - day - night
Rotates on an imaginary axis that passes through the North & South poles. One rotation
is completed every 24 hours.
• for part of this time, earth faces the sun (receiving insolation) - day.
• for the rest of the time, earth faces away from the sun (no insolation) - night.
, Seasons
Winter solstice
21st of June
Shortest day
Autumn equinox Spring equinox
21st of march 23rd of September
Equal day & night Equal day & night
Sun
Summer solstice
21st of December
Longest day
Earth’s revolution - seasons
Earth’s heating isn’t the same throughout the year. Hotter in summer than winter.
Different parts of the world have different seasons at different times of the year. These
seasonal variations are caused by the earth’s axis & revolution around the sun.
If Earth’s axis was vertical,amount of insolation throughout the year would be constant &
there would be no season. However, earth’s axis is tilted at an angle of 23 1/2° & this causes
seasons.
Southern hemisphere:
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