1. Atmosphere and Climate Change
Chapter 13

2. Section 1: Climate and Climate Change

3. Weather and Climate
Weather – the state of the atmosphere in one area at one time.
What is the weather today here?
What is the weather in Anchorage, Alaska?
Climate - the long term prevailing weather at a
particular place
What is the climate for here?
What is the climate for Anchorage, Alaska?
Two places can have the same weather on the same day
But they can have VERY different climates
Weather: Seattle and Phoenix might both have rain today
Climate : Seattle is wet and cool, Phoenix is dry and hot
**It depends on their proximity top the equator.

4. What Determines Climate
Climate is determined by:
Atmospheric Circulation
Patterns
Oceanic Circulation Patterns
Local geography
Solar activity
Volcanic Activity
Which is most important?
Latitude
(How far above/below you are from the equator)

5. Latitude is the distance north or south of the equator
Latitude is the distance north or south of the equator. Measured in degrees.
Equator is 0 degrees, the poles are 90 degrees
Low Latitudes – get the strongest, most concentrated sunlight.
Night and Day are 12 hours, all year round
High temps all year round
High Latitudes – sunlight is spread over a greater area, weaker, less energy
Daylight hours vary
At the poles the sun sets for only a few hours during the summer
Dark almost all day during winter
Average annual temperatures lower than at equator.
Latitude

6. Atmospheric Circulation
Three basic rules: 1. Cold air sinks – but pressure is stronger at lower levels so cold air gets compressed and thus warms. 2. Warm Air Rises – lower pressure lets it expand and it cools down 3. Warm Air holds more water vapor than cold air – so as it rises the water vapor cools and condenses How do we get wind? 1. Sun heats the earth surface. 2. Hot Air Rises 3.Cold Air replaces it………wind!

7. Earth gets heated differently
More heat at equator, more air rising
Rising air cools making lots of clouds! And rain!.(think where are our jungles?)
Cool air can’t sink back down because of continuous rising hot air
Has to spread north and south until it eventually cools enough that it begins to sink…and warm
Dry warm air sinks at 30 North and 30 South
What do we find at 30 North and South around the globe?

8. Prevailing winds – winds that blow predominantly in one direction most of the year.
From what direction does our prevailing wind come from?
(They are deflected to the right in the Northern Hemisphere)
Trade Winds – the prevailing winds between 30° and equator.

9. Ocean Circulation Patterns
Water holds a lot of heat
(think how much heat it
takes to boil water!)
Ocean currents are caused by
winds and the movement of the earth
The ocean currents move heat
around the globe.
In the summer where would you rather swim?
Off California coast in LA or off the South Carolina coast
Colder water flows south from Alaska, warm water flows
north from the Caribbean

10. EL Nino VS La Nina Some ocean currents change the way they flow:
Pacific Ocean water near
Americas warms – leads to
increased clouds and rainfall
in SW US
La Nina
Opposite of El Nino, cooler
waters in Pacific near Americas,
droughts in the SW US
Pacific Decadal Oscillation
Similar to El Nino but the
switching occurs every
20 – 30 years

11. Topography Rain Shadow
Topography is a broad term used to describe the detailed study of the earth's surface.
Where is Mt Kilimanjaro? (Tanzania)
It has snow all year
round!
That’s due to its height
(colder as you go up in
atmosphere!)
Rain Shadow
Dry area on the eastern side of mountains

12. Sun’s Impact Solar Cycle – 11 year cycle of the sun.
Solar Cycle – 11 year cycle of the sun.
At the maximum – the sun emits UV radiation
This can warm the lower atmosphere and Earth.
On earth the Northern Lights can be seen as far south as Mexico on occasion.
Increased radiation from the sun can cause warming of the atmosphere
Seasons – Why do we have them?
All due to the tilt of the earth – 23.5° relative to the plane of its orbit. (Angle of the sun’s rays striking the Earth)

13. That’s all for 13.1
Time for a reading quiz

14. Section 2: The Ozone Shield

15. Ozone Layer Ozone is the chemical compound O3
Large concentration is found in the stratosphere
Ozone Layer absorbs most UV radiation coming from the sun
UV radiation can damage organisms cells
Chemicals Can Destroy Ozone
CFCs – chlorofluorocarbons
CFCs are non flammable, non poisonous, and non reactive at the Earth’s surface
CFCs used as propellants in spray cans and coolants in fridges/air conditioners
It takes years for CFCs to reach the stratosphere from the Earth's surface

16. High energy of the UV radiation breaks it down
CFCs are broken apart in the stratosphere
High energy of the UV radiation breaks it down
The single chlorine from CFC can react with O3 and changes it, depleting the O3
Scientists estimate that a single chlorine atom can break down 100,000 ozone molecules.

17. Ozone Hole
First noticed in 1970 from satellite photos over the South Pole
What Causes it?
During the cold polar winters, dry stratospheric air over the pole is isolated.
Air becomes so cold that it condenses and forms clouds
(Polar Stratospheric clouds: high-altitude clouds made of water and nitric acid at - 80° C)
Chlorine from CFCs builds up on the surface of the clouds
When the pole begins to warm the chlorine goes back to depleting ozone.

18. Video on Ozone Depletion
news/antarctica-ozone-vin/

19. Why Care About Ozone? Ever have a bad sunburn?
UV radiation can damage organisms DNA
Can lead to skin and other cancers
Notable impact to amphibian eggs (death/mutations)
Phytoplankton can be killed by UV
Phytoplankton is the producer for most ocean food chains
Phytoplankton loss would also effect atmospheric CO2 levels
Montreal Protocol
Many nations banned the use of CFCs in 1992 (US stopped production by 2000)
CFCs still a problem….Why?
CFCs molecules remain in the stratosphere for 60 – 120 years

20. That’s all for 13.2
Time for a reading quiz

21. Section 3: Global Warming

22. Greenhouse Effect The earth is like a greenhouse
The atmosphere acts like the glass – which lets the sun’s rays pass through.
The earth absorbs this as heat energy and keeps it in, only letting a little heat out
The gases in the atmosphere absorb the radiation keeping it from escaping out to space
This absorption of radiation by gases is called the greenhouse effect

23. Greenhouse gases
Water Vapor, CO2, CFCs, Methane and NOx all absorb radiation
Water vapor and CO2 are the primary greenhouse gases
Since 1958 (in Hawaii) CO2 levels have been measured – reflective of the entire earth (the gases have traveled across the entire Pacific Ocean)
Levels are higher in the winter: fewer leaves on the trees (dying grasses and leaves release carbon)
General increase because of burning fossil fuels(not just in winter)

24. Global Warming Where does all the CO2 come from? Why be concerned?
Power plants and cars that burn fossil fuels and deforestation
Why be concerned?
CO2 is a greenhouse gas
Scientists believe the increase will warm earth more than normal
Direct correlation between CO2 levels and global warming

25. What Happens If The Earth Warms?
Melting Ice and Rising Sea Levels
Coastal areas flooded
Nearly 3 billion people live
within 100 km of a coast
Excess sea water can change
freshwater aquifers near coasts
Changing Weather Patterns
Warming the oceans could change
currents that influence weather today
Human Health Problems
Deaths due to heat waves
Longer growing seasons, more pollen, more asthma
Warmer weather allow mosquitoes and other disease carrying organisms to live longer

26. Heat leads to droughts, severe impact to crops
Agriculture
Heat leads to droughts, severe impact to crops
May change where plants and animals live
Kyoto Protocol
Nations met and laid out timelines for reducing CO2 emissions
Decrease emissions by 5% from 1990 levels by 2012.
Reducing CO2 is difficult for developing countries
Need industry using cheap fossil fuel to improve economies

27. That’s all for 13.3
Time for a reading quiz