1. Climate and Weather David M. Hassenzahl ENV 206: Introduction to Climate Change

2. Overview Weather and Climate defined Determinants of weather and climate Please read NASA’s Meteorology - Weather And Climate: A Condensed PrimerMeteorology - Weather And Climate: A Condensed Primer

3. Relevant Course Objective Define climate and climate change, and explain how climate changes over time

4. Weather The phenomena (temperature, precipitation, humidity, wind) occurring in the atmosphere at a given time The atmosphere consists of gases held close to Earth by gravity

5. Climate Climate is the typical pattern of weather in a given place over an extended period of time (30 or so years) Temperature Precipitation Humidity Wind

6. Precipitation Type –Rain, snow, fog, other Amount Distribution / Seasonality

7. Temperature Average temperature Daily highs and lows Seasonal highs and lows

8. Humidity and Wind Humidity –Percent of saturation Wind speed matters

9. Winds Uneven heating and cooling lead to winds –Water – Land –Land – Land –North – South –Altitude Earth’s rotation drives winds –Coriolis effect (See video library)

10. Climate and ecology Climate, along with geology, determines what sorts of plants, animals, and other life can live in a given place Humans have developed methods for controlling local climate –Heating and cooling –Building shelter

11. Köppen Classification of Climates Tropical Dry Mild mid-latitude Cold mid-latitude Polar

12. Examples of Climates: Desert Low rainfall (<250 mm / 10 in) per year Low humidity Often hot Mojave (Las Vegas) Sahara, Gobi Source: United States Geological Survey

13. Examples of Climates: Tropical Rainforest 1750 – 2000 mm rain (68 – 78 inches) Year-round or monsoon rain High temperatures and humidity

14. Tropical Rain Forest Source: NASA

15. Examples of Climates Mediterranean Tundra Taiga Steppe

16. Determinants of Climate Insolation Geography Ocean Atmosphere

17. Insolation Aka sunlight Intensity (solar flux) –Watts per square meter Variability –Solar cycles –Solar flares and sunspots Angle of incidence –Earth’s tilt –Varies over time

18. Source: NASA

19. Earth Energy Balance Source: NASA

20. Geography Land masses –Continents –Mountains Water bodies –Oceans –Seas and large lakes Altitude and latitude Albedo (reflectivity)

21. North Pole Ice Source: NASA

22. Ocean Ocean currents move hot and cold water around the globe Evaporation  precipitation Cold air warms up over hot water Hot, humid air condenses, rains when cooled

23. Why Europe is Warm wind direction Warm water flow Source: NASA

24. The Atmosphere Source: NASA

25. Atmospheric Gases Nitrogen – N 2 (~78%) Oxygen – O 2 (~21%) Argon – Ar (~1%) Water vapor (variable, averages 1%) “Trace gases” (parts per million / ppm)

26. Parts per million Parts per million, or ppm As a fraction of volume –(Can also measure by mass) 1 ppm means one atom out of every 1,000,000 atoms in the atmosphere

27. Trace Gases Include Carbon Dioxide – CO 2 –0.0390 % = 390 ppm Methane – CH 4 –1.79 ppm Nitrous oxide (N2O) –320 ppb Chlorofluorocarbons –~1 ppb Neon Helium Krypton Hydrogen Xenon Ozone Others

28. Summary Weather is atmospheric conditions Climate is typical pattern of weather Climate is determined by –Insolation –Geography –Ocean –Atmosphere Next: How Climate Changes