Lecture 1. The Earth’s Atmosphere An extremely thin layer covering the Earth surface What is air? 1 Importance of Water (H2O) Water and its three phases Vapor: invisible Liquid: cloud, rain Ice, snow Ice, hails Æ thunders & lightning Clouds • Change radiation • Release latent heat Water drops Rain Ocean Major greenhouse gases: CO2, CH4, N2O, O3 & SO , CO H2O 2 2 Acid rain Global warming SO2 Æ Aerosols Aerosols affecting clouds CO2 concentration 280 ppm, pre-industrial Æ 380 ppm, present Global warming of 1.4 ~ 5.8 oC by 2100 2 Weather and Climate Weather: day to day variations in temperature, humidity, pressure, wind, cloud, rain Climate: slower variations such as seasonal, year to year, including frequency of extremes Daily-mean air temperature near New York City Unit conversion: English vs. Metric (International System of Units, SI) http://www.digitaldutch.com/unitconverter/ Temperature Length oC = 5/9 (oF – 32) 1 m = 3.3 ft (~ 1 yard) K = oC +273.16 1 mi = 1.6 km Speed 1 knot (1 nautical mile/hr) = 1.15 mi/hr 10 m/s = 22.5 mi/hr 10 m/s = 20 Kts, or m/s x 2 ~ Kts The Mars Climate Orbiter smashed into the planet instead of reaching a safe orbit after a rocket firing September 23, 1999, due to a failure to convert English measures to metric values . 3 Scientific Method 1. Start with an educated guess or “hypothesis” 2. The guess leads to a prediction that can be tested. 3. Design an experiment to test the hypothesis and prediction. 4. Evaluate the results of the experiment to verify or refute hypothesis 5. Construct a theory (or model) based on test results. 6. Repeat cycle (1-5) to refine/modify the theory. Scientific research is an iterative process that constantly rejects false hypotheses and theories. A Brief History of Meteorology ~1450 Cardinal Nicholas de Cusa invented hygrometer. ~1590 Galileo invented thermometer. 1643 Torricelli, a student of Galileo, invented the water barometer to measure atmospheric pressure. Galileo used mercury the next year. ~1650 Pascal and Descartes demonstrated that pressure decreases with height and a famous experiment in the Alps. 1667 Hooke invented swing type anemometer in measure wind speed. 1834 Telegraph invented to transmit observations. 1940’s Weather balloon and weather radars developed. 1950’s Computers applied to numerical weather prediction Æ 1960 The first weather satellite, Tiros 1, was launched. 4 Richardson's "Forecast Factory“, 1922 The "factory" -- really more like a vast orchestral performance -- would have filled a vast stadium with 64,000 people. Each one, armed with a mechanical calculator, would perform part of the calculation. A leader in the center, using colored signal lights and telegraph communication, would coordinate the forecast. The Meteorology Project at Princeton ran its first computerized weather forecast on the ENIAC in 1950. John von Neumann, 2003 - Carl Rossby, Jule Charney 50m x 65m x 17m ENIAC 15 m x 10 m Global Observing System 5 Evolution of Weather Forecast Skills S1-based skill of operational National Centers for Environmental Prediction (NCEP) 500 hPa geopotential height forecasts over the North American region Weather and climate prediction: A great triumph of science El Nino (sea surface temperature) prediction at 6 months lead as compared with observations Future climate projection: A great challenge for science 6 Vertical Structure of the Atmosphere 14.7 pounds/squire inch 1 mb 50 km Sea level pressure 29.92 in. Hg. 10 mb 30 km (weight of air above) 1013 mb (hPa) 100 mb 16 km Weigh the Atmosphere Vacuum (p=0) 30 in. (76 cm) Evangelista Torricelli (1608-1647) on an Italian Stamp. Air pressure is the weight of air above a given height, a hypothesis supported by Torricelli’s own, and subsequent Pascal-Descartes’ experiments. 7 Oxygen (O2) absorption of solar radiation Ozone (O3) Weathers, storms (Lapse rate: 6.5 oC/km) Composition Temperature 8 Thunderstorms along an approaching cold front Satellite view of the weather 9 Anti-clockwise around a low pressure Clock-wise around a high Infrared cloud top Visible temperature Hurricane IOKE Central Pressure: 950 hPa Sustained wind: 100 Kts Developed an eye on August 24 10 Hurricane ILEANA Central Pressure: 955 hPa Sustained wind: 105 Kts 11.