Basic Elements of Weather & Climate

1. Chapter 1IntroductionElements of Weather & ClimateComposition of the AtmosphereThermal Structure of the Atmosphere

2. Basic Elementsof 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 • 0.00003% above 100km

15. Composition of the Atmosphere Below ~ 80 km altitude; Ionosphere exists higher = CO2 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. Stratosphere Temperature in Troposphere and lower Stratosphere Troposphere

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. 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 Temperature CH4 CO2