The document discusses the Earth's energy balance, focusing on the unequal heating of the atmosphere due to varying insolation based on latitude and seasons. It explains how the tilt of the Earth's axis affects daylight hours and seasonal changes, with specific mention of solstices and equinoxes. The document highlights that the Earth's orbit and rotation impact climate and temperature experienced around the world.

1. THE ATMOSPHERE
GEOGRAPHY
GRADE 11
TERM 1

2. UNIT 1: THE EARTH'S ENERGY BALANCE
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3. Unequal heating
of the
atmosphere
Earth is heated by incoming solar radiation(insolation)
The Earth then transfers the heat into the atmosphere
The amount of heat in the atmosphere depends on the amount of
insolation
However, insolation is not equal all over the world
It depends on two factors: Latitudes and Seasons

4. LATITUDES
• Insolation is greatest at the
equator due to more direct
sunlight on a smaller and
closer area
• Insolation decreases as you
get further north or south
from the equator, because
the insolation travels further
and heats up larger areas
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This Photo by Unknown author is licensed under CC BY-SA.

5. SEASONS
• As the Earth revolves around
the sun, different areas will
receive different amounts of
insolation and rainfall, due to
the tilt of the Earth
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6. THE EARTH'S AXIS
The Earth rotates on an
imaginary axis
It takes 24 hours to
complete one rotation
A part of the 24 hours the
Earth faces the sun and
receives insolation
(daytime)
For the rest of the 24
hours, the Earth receives
no insolation (night time)
So the amount of heat a
certain place gets is
dependent on the number
of day light hours it gets

7. The influence of the tilt of the
Earth's axis
• If the Earth's axis was not tilted, all
places on Earth would receive
equal amounts of sunlight per day
and there would be no seasons
• However, the Earth is tilted at 23.5
degrees
• This causes unequal lengths of day
and night, and unequal heating
• In summer, the days are longer with
more heat, than in winter where days
are shorter with less heat
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8. The influence of
the revolution
around the Sun
It takes 365.25 days (1
year) to complete 1 full
revolution
The path it travels is called
an orbit
At each position in orbit,
people in different parts of
the world experience
different seasons

9. This Photo by Unknown author is licensed under CC BY-NC-ND.

10. IN THE SOUTHERN HEMISPHERE
Mid summers day is on the 21st December-
summer solstice. This is characterized by
long warm days and short nights
21stDecember-summer
Mid autumn day 21st of March- Autumn
equinox. This is when the day and the night
are equal in length
21stof March-Autumn
Mid winters day on the 21st of June- Winter
solstice. This is when days are shorter than
the nights with less insolation
21stof June-Winter
Mid spring on the 23rd of September- Spring
equinox. Equal lengths of days and nights.
23rdof September-Spring

11. REFERENCES
Gifts Africa. (2020). Grade
11 Geography Atmosphere
Notes. Available
at: https://gifs.africa/wp-
content/uploads/2020/06
/Grade-11-Geography-
Atmosphere-Notes.pdf
This Photo by Unknown author is licensed under CC BY-SA-NC.