1. The Earth’s Atmosphere
Ch 10-11:
An Overview

2. Overview of the Earth’s Atmosphere
The atmosphere is a delicate life-giving blanket of air surrounding the Earth.
Without the atmosphere the Earth would not have lakes or oceans.
Radiant energy from the sun energizes the atmosphere driving day to day weather.

4. The Earth’s Atmosphere
Composition
99% of the atmosphere is within 30km of the Earth’s surface.
N2 78% and O2 21%, H2O vapors, etc.
The percentages represent a constant amount of gas but cycles of destruction and production are constantly maintaining this amount.

5. Composition %

6. The Earth’s Atmosphere
Composition
Water is a variable gas following the hydrologic (H2O) cycle.
Carbon dioxide has risen in recent years and is an important greenhouse gas.
Other greenhouse gases exist beyond carbon dioxide.
Ozone – surface, upper, large hole above Antarctica
Aerosols (which damage ozone)

8. Ozone Layer

9. Vertical Structure of the Atmosphere
Layers of the Atmosphere
Troposphere: decrease in temperature, day to day weather, tropopause
Stratosphere: increase in temperature, ozone, stratopause
Mesosphere: decrease in temperature, mesopause
Thermosphere: increase in temperature, suns strongest radiation

11. Weather and Climate
Weather: short term air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind
Climate: long term patterns and average weather; not just magnitude but also frequency

12. Weather and Climate Meteorology
Study of the atmosphere and its phenomena
Aristotle 340 B.C. Meterologica, meteoros: high in air
1843 telegraph
1920s air masses
1940s upper air
1950s radar and computers
1960s satellite

13. Meteorologists Special Topic:
Any person with a college degree in meteorology or atmospheric science; not just the TV weather person
Half of 9000 meteorologists employed by the US National Weather Service
Researchers and operational meteorologists

14. Weather and Climate Weather and Climate in Our Lives
Two general reasons for studying how weather and climate impacts our lives: economic efficiency and public safety.
Clothing
Crops
Utilities
Extreme cold and heat
Tornados and hurricanes

15. Weather & Climate A Look at the Weather Map Wind Wind direction
Wind speed
Front

16. Types of Weather Storms of All Sizes Middle-latitude cyclone Hurricane
Thunderstorms
Tornadoes

17. Local Temperature Variations
Southern exposure: warmer, drier locations facing south. Implications for
Vegetation
Viniculture
Ski slopes
Landscaping
Architecture

18. Why the Earth Has Seasons
Earth revolves in elliptical path around the sun every days.
Earth rotates counterclockwise or eastward every 24 hours.
Earth closest to Sun (147 million km) in January, farthest from Sun (152 million lm) in July
Distance not the only factor impacting seasons

20. Why the Earth Has Seasons
Seasons in the Northern Hemisphere
Summer solstice: June 21, Sun directly above Tropic of Cancer, Northern Hemisphere days greater than 12 hours
Winter solstice: December 21, Sun directly above Tropic of Capricorn, Northern Hemisphere days less than 12 hours
Autumnal and Spring Equinox: September 22, Marc 20, Sun directly above Equator, all locations have a 12 hour day

21. Why the Earth Has Seasons
Seasons in the Southern Hemisphere
Opposite timing of Northern Hemisphere
Closer to sun in summer but not significant difference from north due to:
Greater amount of water absorbing heat
Shorter season

22. Why the Earth Has Seasons
Special Topic: First day of winter
December 21 is the astronomical first day of winter, sun passes over the Tropic of Capricorn; not based on temperature