CH. 10 PLANETARY ATMOSPHERES

 Mercury  Made of: helium, sodium, oxygen  No weather-there’s not enough atmosphere! 10.1 PLANETARY ATMOSPHERES

 Venus  Made 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

 Earth  Made 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

 Mars  Made 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 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 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. Reminders: Pay your $5 Turn in permission THIS WEEK! DMA#5 10/9/12

 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 ATMOSPHERIC STRUCTURE

 Describe how the greenhouse effect 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 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 10.2 ATMOSPHERIC STRUCTURE

 Figure 10.9  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? 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 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 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 WEATHER AND CLIMATE

 What are the 2 major factors affecting global wind patterns?  1. Atmospheric heating: the air at the equator heats and expands, then flows 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 affecting global wind patterns?  2. Planetary rotation: basically the rotation of the planet pushes the air sideways-called the Coriolis effect 10.4 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 10.4 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 CLIMATE EARTH VS. VENUS: CLOUDS AND PRECIPITATION

 Mars  Clouds 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 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 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 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