The definitive summary to getting a 90% for Geography in grade 10. This summary's author is Tristan Walker, a student from Uplands college who achieved a 93% average for Geography in grade 10. The summary includes most to all chapters a learner will complete in their quality ten years at an IEB s...
Structure of the atmosphere
3 Spheres (Biosphere)
Atmosphere is the AIr
Hydrosphere is the water
Lithosphere The earth the soil
Why is the atmosphere so important?
○ · Oxygen comes from the atmosphere
○ · It absorbs radiation from the sun.
○ · Burns up meteoroids
○
○ Warms us during the day and keeps us warm in the night
Composition of the atmosphere
● Nitrogen 78 % Needed for plant growth
● Oxygen 21% Produced by photosynthesis needed for respiration.
● Water Vapour 0,03% Reflects radiation source of clouds, keeps global
temperature constant and can be stored as ice.
● Carbon Dioxide 0,00005% Absorbs longwave radiation (Greenhouse gas)
used by plants for photosynthesis
● Ozone Absorbs UV radiation Destroyed by CFC’s
Layers of the Atmosphere
Troposphere
● Lowest layer
● Begins below the surface of the ground to 12Km high
● Warmed by earth's long wave radiation (From rocks etc.)
● Temperature decreases with increase of altitude, Environmental lapse rate 6,4
C per KM.
● Air Pressure falls as gravity decreases
● COntains most of the Water vapour clouds, dust and pollution.
● Tropopause forms upper layer of this here temperature remains =
1
,Stratosphere
● 12- 50Km above sea level
● Increase in Temperature here due to concentration of Ozone (Ozonosphere)
● Absorbs the most UV radiation
● Protects us from meteoroids
● Temperature in Stratopause remains constant
Mesosphere
● 50- 80 Km above sea level
● Temperature here falls rapidly due to the lack of atmospheric particles to absorb
radiation.
● Atmosphere strongest winds 3000 Km/H
● Meteoric dust and ice form condensation nuclei which reflects creating a noctilucent
Thermosphere
● Upper layer 80–480 KM above sea level
● Rapid increase of temperature with an increase up to 150 C
● High temperatures result in very strong solar radiation
● Atomic oxygen absorbs UV radiation like ozone here
● The Vibration of the Oxygen molecules allow radio waves from one location to be
received beyond the horizon.
Atmospheres Density and pressure
Earth's Gravitational pulls the gases and liquids and solids toward the ground so there are
more gas molecules and fewer as you move away from the crust. Atmospheric pressure as
the weight of the overlying column of air. More dense = Higher pressure
The Ozone layer (Stratosphere)
Occurs in a low concentration form of oxygen and has 3 oxygen atoms essential for
absorbing UV radiation, This is measured in PPM parts per million. It occurs naturally any
thinning of the ozone layer allows more radiation to reach our surface. 15-30KMM above sea
level
What causes Ozone depletion?
● Chlorofluorocarbons (CFC’s) in Spray cans and fridges
● Halons in fire extinguishers
● Methane from fossil fuel production and cattle.
● Methyl bromide- Used in pesticides. Ozone (DU) Dobson unit
2
,Processes associated with heating of the
Atmosphere
How is insolation (Incoming solar radiation) Distributed?
When insolation from the sun, (Short wave radiation) is dispersed in different ways.
Absorption- Clouds intercept as they cover 3% of solar energy absorbed by dust particles
and gases (Ozone) 16%. 19 % of the radiation energy is absorbed by the atmosphere. 51%
reaches the surface and 4% reflected back by land surfaces.
Scattering- This occurs when radiation is scattered by atmospheric particles of dust or gas.
Reflection- Clouds and water bodies and land itself reflects large amounts of radiation back
into space. The sun's energy is lost in this way and does not warm our atmosphere, light
shiny surfaces reflect more than darker surfaces
12% Scattered 6% in and 6% out
51% Absorbed
49% Reflected 20% Clouds 4% Water.
How is energy transferred from the earth's surface?
● Radiation - Shortwave radiation reach the ground and changed into longwave
radiation back into the atmosphere (Hand above stove)
● Conduction - within the first metre of the atmosphere energy is physically transferred
from one molecule to another this is rapid (Pot of water above stove)
● Convection - Heat energy is distributed by movement of heat molecules (Mirage)
strong vertical movement of air all over all land surfaces
The earth is directly responsible for our heat. We need the long wave radiation.
Factors that affect temperature
1. Latitude
The amount of direct sunlight more equator less polar regions. More atmosphere
molecules mean less light can hit the earth. light is reflected by the ice.
2. Altitude
CO2 and H2O Vapour absorbs heat hence higher altitude colder the temperature.
3
, 3. Ocean Currents
Cold ocean currents originate at the poles, The warm currents and cold ocean
currents try to correct imbalance so they flow to each other which creates hot cold air
above them.
4. Distance from the ocean
They work differently in terms of the insolation, maritime/continental climates. Water
transparency absorbs and mixes the sun’s rays, takes longer to warm while the land
reflects but mostly absorbs.
The closer to the ocean at night temp falls less but takes longer to warm in the
morning.
The greenhouse effect
Temperature profiles
The first one is the normal environmental lapse rate the second is the
Inversion temperature, this occurs when no wind at night causes cold and warm air to not
mix and since hot air rises leves the cold air at the bottom making it warmer as you go higher
in altitude until you escape the Inversion layer. A result of Terristial radiation, earth relases
radiation absorbed during the day
4
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