CH. 10 PLANETARY ATMOSPHERES
MercuryMade of: helium, sodium, oxygen
No weather-there’s not enough atmosphere!
10.1 PLANETARY ATMOSPHERES
VenusMade of: mostly Carbon dioxide (96%) and a little Nitrogen (3.5%)
Weather-slow winds with no big storms and lots of acid rain from sulfuric acid clouds
10.1 PLANETARY ATMOSPHERES
EarthMade of: mostly
Nitrogen (77%) lots of Oxygen (21%), argon, water vapor, and other trace elements
Wind over the whole planet-global wind patterns, storms, hurricanes
Clouds made of water vapor
10.1 PLANETARY ATMOSPHERES
MarsMade of: mostly Carbon dioxide (95%), Nitrogen (2.7%) and Argon (1.6%)
Weather-some wind and dust storms, but there is very little pressure and the atmosphere is very thin
10.1 PLANETARY ATMOSPHERES
Video from Discovery Streaming
WEATHER ON MARS
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
10.1 PLANETARY ATMOSPHERES
3 things that would 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 surface2. How much sunlight the
planet absorbs vs. refl ects3. 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
10.2 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
10.2 ATMOSPHERIC STRUCTURE
Is the greenhouse
effect a good thing or a bad thing?Explain.
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Layers of the atmosphere
10.2 ATMOSPHERIC STRUCTURE
7. 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!
10.2 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
10.2 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.
10.2 ATMOSPHERIC STRUCTURE
Describe how the greenhouse eff ect works and why it is important to life on Earth.
Light from the sun warms the atmosphere and ground
The “greenhouse” gases absorb heat, then re-emit it in all directions
This helps heat the surface and keeps the troposphere warm
Importance?Because it keeps us warm and
regulates our temperatures so we don’t have very extreme temperature shifts
10.2 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 stratifi ed
Airplanes glide smoothly here because of the lack of air movement.
How does the ozone in the stratosphere benefi t us?
It absorbs most of the Sun’s UV radiation, which is very damaging to us
10.2 ATMOSPHERIC STRUCTURE
Figure 10.9a. Which one of the
three planets shows the biggest temperature increase due to the greenhouse eff ect?
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?
10.2 ATMOSPHERIC STRUCTURE
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
10.3 MAGNETOSPHERES AND THE SOLAR WIND
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
14. What is the diff erence 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
10.4 WEATHER AND CLIMATE
15. Why doesn’t Venus experience seasons?
Because it isn’t tilted! Both hemispheres stay in the same location relative to the Sun.
10.4 WEATHER AND CLIMATE
What are the 2 major factors aff ecting global wind patterns?
1. Atmospheric heating: the air at the equator heats and expands, then fl ows towards the poles and sinks, creating convection cells
Let’s compare Earth and Venus…
10.4 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 aff ecting global wind patterns?
2. Planetary rotation: basically the rotation of the planet pushes the air sideways-called the Coriolis eff ect
10.4 WEATHER AND CLIMATE
How does the Coriolis eff ect 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
10.4 WEATHER AND CLIMATE
Similarities:
Sun warms the atmosphere at the equator and creates convection cells
Clouds are always present
Clouds contain water
Rain forms and falls
Differences:
On Venus-Clouds contain Sulfuric acid mixed with the water(both of these are replenished by volcanic eruptions)
Rain that falls evaporates long before it hits the ground
10.4 WEATHER AND CLIMATEEARTH VS. VENUS: CLOUDS AND
PRECIPITATION
MarsClouds can form-
especially over its big volcano-Olympus Mons
Barely any water in the atmosphere, but there is some hidden under the polar CO2 ice caps
There may be more water under the surface that helps form the geologic features of Mars
10.4 WEATHER AND CLIMATE
How are atmospheres created?
From 3 diff erent 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
10.5 ATMOSPHERIC ORIGINS
AND EVOLUTION
20. What is outgassing? Why is it important?
It’s important because it helps create and replenish atmospheres
21. What are some ways an atmosphere can lose gas? Thermal escape-a molecule moves fast
enough to escape gravity Bombardment Atmospheric cratering Condensation Chemical reactions
10.5 ATMOSPHERIC ORIGINS AND EVOLUTION
What are the 3 things 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
10.5 ATMOSPHERIC ORIGINS AND EVOLUTION
23. The Moon and Mercury: what is their only source of new gas?
Bombardment from micrometeorites
How do they lose gas particles?
Both are small so they have low gravitational pull and the particles can move fast enough to escape
Other times they are stripped away by solar wind
10.6 HISTORY OF THE
TERRESTRIAL ATMOSPHERES
24. Mars: what stripped away the majority of its atmosphere?
it’s possible that Mars used to have a thick atmosphere from volcanic outgassing
As the planet cooled it lost its magnetosphere
the atmosphere was then stripped away by the solar wind
10.6 HISTORY OF THE TERRESTRIAL ATMOSPHERES
25. Venus: Why is it hotter than Mercury even though it is further from the Sun?
What is one piece of evidence that Venus may have once had a lot of water vapor in its atmosphere?
An unusually high amount of deuterium-an isotope of hydrogen that can be left behind when water molecules are broken apart by UV radiation.
10.6 HISTORY OF THE TERRESTRIAL ATMOSPHERES
Reflection-Answer in your notebooks 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