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Transcript
Lecture 1 Lecture 1 Outline of Today’s Lecture • • • • • • What is it that defines science? What is meteorology? A brief history of meteorology. What does the atmosphere do for us? What is the atmosphere composed of? Intro to atmospheric structure 1 Science 2 Scientific Method 1. Start with an educated guess or “hypothesis” 2. The guess should 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. • What is it that defines science? • How is science distinguished from other academic endeavors (e.g, history or comparative religion)? • Why is creationism not considered science by scientists? 3 4 Scientific Method What is Meteorology? • Our understanding of the world grows as our theories become more complete and precise. • The term meteorology comes from the Greek word meteoros, meaning, “high in the air.” • A key to the Scientific Method is that the results of a good experiment are reproducible. The same experiment using the same hardware will produce the same results time after time. • Rain and snow are hydrometeors. • Meteorology is the study of the atmosphere and the processes that produce weather. • If a hypothesis can not be tested then it falls outside the current realm of scientific understanding or knowledge, and is considered “speculation.” • Meteorology is also called atmospheric science. 5 A Brief History of Meteorology 6 A Brief History of Meteorology Answer: Lack of instruments to make observations. 340 BC In a book he called Meteorologica, the Greek philosopher Aristotle was the first person to organize and record his weather thoughts in a systematic way. ~330 BC A student of Aristotle, Theophrates, wrote first book on weather forecasting. ~200 BC Hero developed crude water thermometer. ~1450 Cardinal Nicholas de Cusa invented hygrometer. ~1590 Galileo invented thermometer. 1643 A student of Galileo, Torricelli, 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. For nearly 2000 Years we have a Big Blank in progress Why? 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 High Speed Computers invented and applied to weather prediction. 1960 The first weather satellite, Tiros 1, was launched. 7 8 What does the Atmosphere do for us? The atmosphere moderates temperatures near the Earth's surface • Contains the oxygen that humans require for breathing. • Sound requires a medium to travel through. • Provides for a Hydrological cycle • Atmospheric "Greenhouse Effect" – Without the atmosphere, the average surface temperature of the Earth would be about 0 °F – Due to "Greenhouse Effect", the average surface temperature is about 59 °F • Reduces diurnal temperature swings -- without the atmosphere, the days would be much hotter and the nights much colder – {Evaporation of water from surface} à {Condensation in clouds} à {Rain or snow} • Shields the Earth from harmful ultraviolet radiation • Atmosphere moderates temperature near Earth’s surface – Mercury’s daytime temperature is 700 °F – Mercury’s nighttime temperature is -300 °F • Transports energy from the tropics to the poles otherwise tropics would be much warmer, poles much colder 9 Vertical Structure of Atmosphere 10 Thickness of the Atmosphere • The atmosphere becomes thinner with height • There is no easy way to establish the “top” of the Earth’s atmosphere 11 12 Thickness of the Atmosphere The atmosphere is a thin blanket of "air" -- a mixture of mostly gases and some aerosols. • Top of a thunderstorm = ~12 km • 100 km above sea level - 99.99997 % of the atmosphere is below this height 1. Gas -- substance in which individual atoms and molecules are not chemically bound together. Different from liquids and solids. Aerosols -- tiny liquid or solid particles that are suspended in the air, most are too small to be seen individually 2. • • cloud droplets (liquid) dust, sea salt, smoke, volcanic ash (solid) 13 14 Permanent Gases* % of total (excluding water vapor) Lubbock Aerosols Nitrogen (N2) 78% Oxygen (O2) 21% 99% * This is true for the lowest ~50 miles or 80 kilometers. 15 16 Vertical Structure of the Atmosphere Variable Gases Variable Gases % of total Water Vapor (H2O) 0.01% - 4 % Carbon Dioxide (CO2) 0.036 % 365 (increasing) Ozone (O3) 0.000004 % 0.04 (troposphere) 0.002% 0.0002 5 – 12 (stratosphere) Chlorofluorocarbons(CFC) Layers in the atmosphere PPM (parts per million) – – – – (most at surface) Density Chemical Composition Electrical Characteristics Temperature Aerosols (NOT gas) 0.000001% Air Pollution -- Elevated levels of aerosols or harmful gases 17 Characterizing with Chemical Composition 18 Characterizing with Temperature • Homosphere - Region within ~80 km of the Earth’s surface where there is chemical homogeneity. • Heterosphere - Located above the Homosphere where lighter gases become more dominant with height. Standard Atmosphere – – – – 19 Troposphere (lowest) Stratosphere Mesosphere Thermosphere (highest) 20 Characterizing with Temperature Characterizing with Temperature 21 Troposphere 22 Tropopause The warm air of the stratosphere acts as a lid on updrafts in the troposphere. The stratosphere is warm because of absorption of UV sunlight by ozone. 23 24 Overshooting Thunderstorm Characterizing with Electrical Composition • Ionosphere – Layer extends from the upper mesosphere into the thermosphere. – It contains large numbers of electrically charged particles called ions. • Ions are formed when electrically neutral atoms or molecules lose one or more electrons and become positively charged. (solar energy) Anvil Cloud – Responsible for the aurora borealis (northern lights) 25 Summary 27 26