1. Chapter 1 Introduction Elements of Weather & Climate Composition of the Atmosphere Thermal Structure of the Atmosphere

2. Basic Elements of Weather & Climate
Temperature
Humidity
Clouds
Precipitation
Air Pressure
Wind

3. Hypothetical Winter Weather

4. Weather is important atmospheric conditions at a point in time
What’s portrayed:
Temperature
Precipitation
Cloud cover
Air pressure (crudely only)
Also important:
Wind
Humidity

5. Temp. at one place over time
(temp-erature “time series”)
Salt Lake City Temperatures Dec 07
Observed, Normals, Records

6. Salt Lake City Temperatures 2007 –Observed, Normals, Records

7. Temperature Measurement
Thermometer

8. Anemometers

9. Thermometer
Barometer

10. Tipping Bucket Rain Gauge

12. Thickness, Composition & Thermal Structure of the Atmosphere
Thickness = pressure and density of air decrease with elevation
Chemical composition = elements (gasses) that make up air and remain nearly constant (so ignoring water, aerosols [very fine dust], pollution)
Thermal Structure = How temperature changes with elevation in the atmosphere

13. Atmosphere Thickness and Pressure
Pressure is caused by weight of air above, so pressure decreases with altitude
Pressure compresses air, so air becomes less dense or ‘thinner’ with altitude
Atmosphere has no distinct top; it just becomes less and less dense until for practical purposes there is no air, above ~ 100 km
Note: 1 km = 0.62 miles

14. Atmosphere Thickness and Pressure
Sealevel Pressure =
14.7 lb/in2 or 1013 mb or 29.9 inches (of mercury)
Orem Pressure =
12.5 lb/in2 or 855 mb
Where is the air?
50% below 6km altitude
90% below about 18km
% above 100km

15. Composition of the Atmosphere Below ~ 80 km altitude; Ionosphere exists higher
Oxygen gas = O2
Nitrogen gas = N2

16. Gasses in Dry Air N2 (‘Nitrogen’) – 78% O2 (‘Oxygen’) – 21%
Ar (Argon)– 1%
CO2 (Carbon dioxide) – 0.37%
Ne (Neon), He (Helium), CH4 (Methane), Kr (Krypton), H2 (Hydrogen) – < 0.002%

17. Other, Variable Components of Air
Water Vapor (H20) – 0 to 4%
Aerosols (dust)
Ozone (03)
All are important!

18. Water on Earth

20. Aerosols Examples include dust and air pollution
Aerosols are variable in concentration and location

21. Ionosphere Exists above ~ 80 km
Radiation from Sun knocks electrons off gas molecules & atoms, ionizing them
Ionosphere protects lower atmosphere from radiation by absorbing the energy (meaning we need it!)

22. Thermal Structure of the Atmosphere
Temperature changes with altitude create 4 distinct layers to the atmosphere:
Thermosphere – Above stratos.; T increase w/ height
Mesosphere – Above stratosphere to ~ 90 km; T decreases w/ height
Stratosphere – Above troposphere to ~ 50 km; T increases w/ height
Troposphere – Ground to 10 – 15 km altitude; T decreases w/ height. Weather happens in this layer!

23. Temperature in Troposphere and lower Stratosphere

24. The Atmosphere Interacts With the Whole Earth

28. Weather affects many of our activities
Weather events can be very expensive (droughts!)
Weather can be deadly (droughts!)

30. Lithosphere Atmosphere Hydrosphere Biosphere
Earth’s Four Spheres
Lithosphere
Atmosphere
Hydrosphere
Biosphere

31. The Earth System
Earth

32. Atmospheric Carbon Dioxide

33. Modern Atmospheric Greenhouse Gas Concentrations and Temperature
CH4
CO2
Modern Atmospheric Greenhouse Gas Concentrations and Temperature