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Planetary atmospheresCHAPTER 10 SECTIONS 10.1 & 10.2
Discuss the factors that affected the geologic processes and formations of the planets
Outline the information in the 6 slides
Use Chapter 10, sections 10.1 and 10.2 , pages 280 - 295 to add further detail.
Highlight the detail that you add
Refer to your vocabulary to be sure you understand the concepts
Planetary Atmospheres
Planetary Atmospheres
What is an atmosphere? the layer of gases that
surround a world can be either molecules or
atoms which create pressure-we feel the pressure of 1 atm, on Venus we would feel the pressure of 90 atmospheres
Where does the atmosphere end?
There’s not a specific ending place-it kind of fades away
Atmospheric Structure
3 factors that determine how sunlight would heat a planet with no atmosphere:
1. Distance from the Sun the closer it is, the more energy
from sunlight reaches the surface
2. How much sunlight the planet absorbs vs. reflects
3. How fast the planet rotates if it has a short day, the
temperatures will be more even than if there is a really long day
Atmospheric structure
How does an atmosphere keep a planet warm?
Gases can absorb infrared light and heat up
Greenhouse gases trap infrared radiation and this helps heat the lower atmosphere (where we live!)
The greenhouse gases are gases that are good at absorbing infrared light: Water vapor Carbon dioxide Methane
10.1 Atmospheric Structure
Layers of the atmosphere
10.1 Atmospheric Structure
How does the fact that our atmosphere scatters light benefit us? What would it be like if our atmosphere didn’t scatter light?
Without scattering we would be able to see the stars during the daytime!
Also, shadows would be pitch black, so walking down the alley in a big city would be like night!
Atmospheric Structure
Why is the sky blue? Light scattering
makes the sky appear blue
Blue light is scattered while the red light goes straight through the atmosphere
Atmospheric Structure
Why do sunsets appear red? Sunlight passes through more
atmosphere to reach you-most of the blue light is “scattered away” leaving the red behind.
10.1 Atmospheric Structure
Why is the stratosphere called the stratosphere?
There isn’t any convection, so the air isn’t moving much and becomes layered-AKA stratified
Airplanes glide smoothly here because of the lack of air movement.
How does the ozone in the stratosphere benefit us?
It absorbs most of the Sun’s UV radiation, which is very damaging to us
Atmospheric Structure
Figure 10.9 Very important!! a. Which one of the three
planets shows the biggest temperature increase due to the greenhouse effect?
b. Which planet has the most uniform temperature from high to low altitude?
c. Is the Earth’s temperature higher at and altitude of 25km or 50km?
Magnetospheres and the Solar Wind
Why is the magnetosphere so important to us?
Solar wind = charged particles from the Sun The magnetosphere will either divert those
particles or trap them in the Van Allen Belts
They can produce beautiful auroras in the North and South poles-where the North and South poles of the magnetosphere come close to the Earth’s surface
MAGNETOSPHERES AND THE SOLAR WIND
Weather and Climate What is the difference between
weather and climate? Weather is the varying
conditions and combinations of wind, clouds, temperature, and pressure
Can change with the seasons and atmospheric conditions, can vary dramatically by the month, day or even hour
Climate is the long term average of all the weather in an area and generally stays the same over long periods of time
What are the 2 major factors affecting global wind patterns?
Atmospheric heating: the air at the equator heats and expands, then flows towards the poles and sinks, creating convection cells
Rotation and Coriolis Effect: Coriolis effect alters the path of the air due to the rotation of the Earth like a merry go round
10.2 Weather and Climate
The circulation of the Venusian atmosphere is dominated by two huge convection currents in the cloud layers, one in the northern hemisphere and one in the southern hemisphere
What are the 2 major factors affecting global wind patterns?
Planetary rotation: basically the rotation of the planet pushes the air sideways-called the Coriolis effect
Weather and Climate
How does the Coriolis effect change the shape and movement of the circulation pattern of winds on Earth? Breaks up the convection
cells so there are 6 instead of 2 (3 per hemisphere)
Causes air to circulate counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere
10.2 Weather and Climate
How are atmospheres created? From 3 different processes
Outgassing-the outpouring of gases from the earth's interior
Evaporation/sublimation-surface liquids evaporate into the atmosphere
Bombardment-micrometeorites can create only a very thin atmosphere, this is the main source of atmosphere for the Moon and Mercury
Atmospheric Origins and Evolution
10.5 Atmospheric Origins and Evolution
Outgassing from volcanism on Earth, Venus and Mars releases water, carbon dioxide, nitgrogen and sulfuric gases
Evaporation and sublimation from the surface adds gases as the planet surface warms
Bombardment by micometeorites ejects surface materials including gases and explains even the small amount of atmosphere around the Moon and Mercury
Gaining Atmosphere
10.2 Atmospheric Origins and Evolution
Thermal escape occurs as particle are heated and reach escape velocity
Bombardment and atmospheric cratering result from solar wind particles stripping.
Condensation of atmospheric gases on the surface occur with cooler temperatures. Mars has dry ice on its surface
Gases chemically react with the surface, like oxygen
Losing Atmosphere
What are the 3 factors that determine if a gas can be lost by thermal escape?
1. The planet’s escape velocity-the larger the planet the stronger the gravity
2. Temperature-higher temperature means faster movement
3. Mass-it’s easier for lighter particles to move fast enough to escape
Atmospheric Origins and Evolution
Reflection-Extra Credit! What makes our
atmosphere so unique and suitable for life?
Give at least 4 pieces of evidence to support your claim.
Include information on the atmospheres of at least 2 other terrestrial planets in comparison with Earth.
Terrestrial Atmospheres
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