1. The Atmosphere By the end of the day, you will be able to:
Identify the main components of air
Explain the importance of the atmosphere to life on Earth

2. Essential Question
Why is the Earth the only place in the solar system that supports the diversity of life as we know it?
Deep in space, the temperature is -450° F
Closer to our Sun, temperatures reach thousands of degrees Fahrenheit.
What makes Earth's climate so moderate?

3. The Atmosphere
Critical Question: In what ways does the atmosphere make the Earth suitable for life?

4. What is the Atmosphere?
A mixture of gases that surrounds the Earth

5. Gases of the Atmosphere
Major Components
The majority of the atmosphere is made up of Nitrogen, N2 (78%)
The second most common gas in the atmosphere is Oxygen,O2 (21%)

6. Gases of the Atmosphere
Variable Components
The remaining 1% is made of Argon, CO2, water vapor, dust, volcanic ash, salt, smoke, ozone (O3), and other gases

7. What prevents the atmosphere from escaping into space?
Earth maintains an atmosphere because of its gravitational pull

8. Why is the Atmosphere Important?
Case Study: THE MOON
Life cannot exist naturally on the moon because there is no atmosphere!

9. Why would life on the moon be difficult?
No air to breathe (O2)
Temperatures are extreme: oC (night) to 100oC (day)
There’s no atmosphere so all the heat escapes at night
Temperature on the Moon (3)
Intense UV radiation (no ozone)
No atmospheric pressure (no liquid water)
No weather (wind = moving air)

10. Why is the Atmosphere Important?
The atmosphere makes conditions on Earth suitable for living things
(LIFE COULD NOT EXIST WITHOUT IT!)

11. Why is the Atmosphere Important?
Water Cycle
Provides a place for water vapor to travel around the globe
The water cycle depends upon the atmosphere
Weather happens in atmosphere

12. Why is the Atmosphere Important?
Ozone Layer
The ozone layer protects life from the sun’s ultraviolet rays
All of the ozone combined would only create a layer 3mm thick

13. What is Ozone?
a colorless unstable toxic gas with a pungent odor and powerful oxidizing properties, formed from oxygen by electrical discharges or ultraviolet light. It differs from normal oxygen (O2) in having three atoms in its molecule (O3).
Waht is Ozone? (7 min.)

14. Why is the Atmosphere Important?
Oxygen & other gases required to sustain life.
No other place in our solar system has oxygen in the atmosphere!

15. Why is the Atmosphere Important?
Liquid Water
The weight of the atmosphere allows liquid water to exist on Earth
The atmosphere is ~ 62 miles high
62 miles of air pressing down on your head creates ~14.6 lbs of pressure (at sea level)
Atmospheric pressure prevents water from turning to a gas

16. Why is the Atmosphere Important?
The greenhouse effect
Greenhouse gases (carbon dioxide, water vapor, methane…) trap heat
Without the green house effect, Earth would be much colder
Liquid water would be ice instead (ice age)

17. Why is the Atmosphere Important?
Meteorites
Protects the Earth’s surface from small (<car-sized) meteors
Millions of space rocks vaporize in the Earth’s atmosphere each day (mostly sand-sized)
Chelyblinsk Meteorite

18. The Atmosphere By the end of the day, you will be able to:
Identify the main components of air
Explain the importance of the atmosphere to life on Earth

19. The Atmosphere By the end of the day, you will be able to:
Describe the relationship between altitude and air pressure.
Describe the relationship between altitude and temperature.

20. Atmosphere and Altitude
Critical Question: Explain how the atmosphere changes with altitude.

21. Why is it harder to breathe at higher altitudes?
The density of air changes with altitude
As you climb higher, the air becomes less dense
Density = mass per unit volume
There are less air molecules in each breathe (less oxygen)

22. Why do sealed containers expand when transported over the pass?
Air pressure changes with altitude
Air pressure is the amount of force caused by air molecules pushing on an area
Air pressure is higher at sea level because the air is dense and there is more of it on top of you

25. 3. Water boils at a lower temperature in the mountains because there is less air pressing down on the water surface

26. Importance of Atmospheric Pressure
Why does water boil?
At NASA’s Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65.
He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain.
The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds.
The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.
NASA air pressure (3)

27. Atmospheres of the Inner Planets
Critical Question: Describe how the Earth’s atmosphere compares to other inner planets.

28. What if the Earth’s atmosphere was like Mercury’s?
You could not breathe – not enough air
Mercury does not have enough gravitational pull to hold much of an atmosphere

29. What if the Earth’s atmosphere was like Mercury’s?
Temperature range is extreme: -170oC (night) to 430oC (day)
At night, all the heat escapes into space because there’s no atmosphere to trap it
Mercury is similar to the Earth’s moon because they both lack atmospheres, have extreme temperatures, and are covered with craters

30. What if the Earth’s atmosphere was like Venus’?
Venus’ atmosphere is so thick that every day is a cloudy one (no sunny days)
You could not breathe – mostly CO2 and sulfuric acid
You would be crushed by the weight of the atmosphere (90x greater than atmospheric pressure on Earth)

31. What if the Earth’s atmosphere was like Venus’?
The thick CO2 traps heat from the sun (greenhouse effect) causing temperatures to reach 470oC
Even though Venus is further from the sun than Mercury, differences in atmosphere thickness make Venus have the hottest surface temperature of all the planets

32. What if the Earth’s atmosphere was like Mars?
You could not breathe (mostly CO2)
Temperatures range from -13oC to -77oC
The atmosphere is not very dense so it cannot trap enough heat (not enough of an greenhouse effect)
The air pressure is so low that any liquid would boil away

33. The Atmosphere By the end of the day, you will be able to:
Identify the main components of air
Explain the importance of the atmosphere
Determine whether air has mass or volume.
Describe the relationship between altitude and air pressure.
Describe the relationship between altitude and temperature.