# GG101 Study Guide - Midterm Guide: Geostrophic Wind, Pressure Gradient, Shortwave Radio

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Published on 16 Oct 2011
School
WLU
Department
Geography
Course
GG101
Part I: The energy-atmosphere system
Part I_2
What controls strength of sun waves?
Distance of the sun. earths revolution around sun and its tilt, atmosphere filtering effect.
Solar Constant
Solar constant of 1400 w/m2 once sun rays get to earth
Equinox position:
Everywhere has 12 hours of day and 12 hours of night
When sun sees both poles at same time
Sub solar point at equator
Happens twice in a year. Fall and spring
Equal amount of light hitting north and south. North=south
Winter solstice:
Sub solar point is the condition of the earth where sun is directly over head.
90 degrees over on horizon.
Axis line is 23.5* north of light
24 hour darkness in North
Sub solar point 23.5* south of equator
Summer Solstice
Sub solar point Is 23.5* north of equator
24 hour darkness in South
Geometric positions are important because they control position of sub solar point and therefore angle
of indication. Angle of incidence is important because energy from sun is diluted in low angle positions
and less diluted in high angle positions.
Tilt of the axis causes seasons. Seasons are effective way of distributing energy. If no tilt than we would
have hotter equator and colder poles.
Sun degree is 26* during Winter, 50* during Spring, fall and 73* during Summer solstice.
Time of day/year (Check slides for graph)
What Controls Angle of Incidence?
Latitude, time of day, time of year
Solar Energy to Earth and the Seasons
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
1. Nature and forms of radiation
Wavelength is a measure of solar radiation.
- Long wave and short wave
2. Laws governing energy flows
Energy is in equilibrium. Moves from surplus to deficit
Rate of energy movement is proportional to energy gradient. Energy moves through colder things faster
Energy cannot be created or destroyed (conservation of energy)
I= t+a+
3. Laws Describing Radiation from surfaces
The Electromagnetic Spectrum
Long waves are in lower half. Short waves are top half. Both can be broken down into components.
Short wave is the light that we can see.
1) Inverse relationship between temperature of an object and wavelength it emits

b is cons
Explains horizontal difference in graph
2) Flow of radiant energy from a surface is directly related to the surface energy to the fourth
power. Increase temperature of the surface a little bit, you increase the temperature of
The wavelength of maximum intensity radiation grows longer as the absolute temperature of the
Stefan-Boltzman law: M = T4
Explains vertical difference in graph
4. Budgets of radiation and energy


With filter 1400 w/m2 square radiation but around 500 is transmitted.
If no filter than all is transmitted
Filter causes radiation to be transmitted, absorbed or reflected. The ground does the same thing.
Depends on ground properties. Ex. Snow has better reflective properties than asphalt.
Atmosphere also varies. About 10000km deep, 97% within ground and 30km above.
78% nitrogen
21% oxygen
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1% argon, Carbon Dioxide, Water vapour
Green house gasses (absorb long waves). Increase the absorption of energy and warms atmosphere.
Warm air
Photosynthesis respiration
Vary in concentration
Combustion
mperature is going to rise.

Clouds can cause absorption of 5-20% and reflection of 35-60%. So only 45-10% reaches the ground.
Filter is not a constant thing, but is more dynamic.
Atmospheric filter:
- reduces by absorbing and reflecting energy
- It also transforms absorbed short wave energy into long wave energy. If reflected it stays short
wave.
- It also scatters energy. Direct and diffuse.
I= T+a+alpha
- if it reflects off something in
atmosphere and  reach the ground.
- t
- 
absorbing the long wave energy.
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