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Chapter 1: The Earth’s Atmosphere Overview of the Earth’s atmosphere Vertical structure of the atmosphere Weather and climate Q: You can live for a few minutes only: a) without air b) without water c) without food

Overview of the Earth’s Atmosphere when the earth is scaled to the size of an apple, 99% of atmosphere is no thicker than the skin on an apple Water vapor molecules are invisible: clouds; sink: condensation/deposition source: evaporation/sublimation transpiration Fig.1.2

Composition of the Atmosphere permanent gases Nitrogen source: decaying of plant and animal matter sink: soil bacteria; ocean plankton Oxygen source: plant photosynthesis (sun + CO2 + H2O lead to sugar and O2) sink: organic matter decay breathing (take in O2, release CO2)

Q: which is the most important greenhouse gas in the atmosphere? a) water vapor; b) carbon dioxide; c) methane, d) ozone 380 ppm = 380/106 = 380 * 10-4/102 = 0.038% Table 1-1, p. 3

Composition of the Atmosphere Carbon dioxide and the greenhouse gases ozone aerosols pollutants Ozone at high altitudes (stratosphere) is “good”; ozone at low altitudes (troposphere) is “bad.” Fig. 1.4

Q: List three sources and two sinks of CO2 in the atmosphere Stepped Art Fig. 1-3, p. 4

The Early Atmosphere the first atmosphere: hydrogen, helium outgassing and the second atmosphere water vapor, carbon dioxide, nitrogen evolution of the atmosphere: carbon dioxide and oxygen The evolution of life and the atmosphere are closely linked.

Vertical Structure of the Earth’s Atmosphere Radiosonde launched twice a day to measure temperature, humidity, wind, and pressure of the lowest 30 km above surface Q: where is the balloon launched in Tucson? a) airport; b) Mt. Lemmon, c) UA campus

A Brief Look at Air Pressure and Air Density air density: mass per unit volume air pressure: air weight above a level sea-level pressure Surface pressure: 1013 mb = 1013 hPa = 29.92 in.Hg Q: Baseballs travel farther in higher-altitude air (Denver) than they do in lower-altitude air: true or false?

Figure 1.7: Both air pressure and air density decrease with increasing altitude. Fig. 1-7, p. 8

b) 23% Q: what is the percentage of O2 at the top of Mt. Everest compared with sea level? a) 13% b) 23% c) 33% d) 43% Figure 1.8: Atmospheric pressure decreases rapidly with height. Climbing to an altitude of only 5.5 km, where the pressure is 500 mb, would put you above one-half of the atmosphere’s molecules. Fig. 1-8, p. 9

Layers of the Atmosphere vertical temperature profile Troposphere lapse rate: 6.5degC/1km; temperature inversion Stratosphere O3 absorption mesosphere Thermosphere O2 absorption

The Ionosphere electrified regions of the atmosphere D, E and F regions radio waves When the radio was invented by G. Marconi in the early 20th century, it was not known how radio waves traveled long distances through the atmosphere.

Figure 1.11: At night, the higher region of the ionosphere (F region) strongly reflects AM radio waves, allowing them to be sent over great distances. During the day, the lower D region strongly absorbs and weakens AM radio waves, preventing them from being picked up by distant receivers. Fig. 1-11, p. 13

Weather and Climate Satellites Radar Radiosonde Aircraft Weather station See ATMO web site

Elements of Weather air temperature air pressure humidity clouds precipitation visibility wind Certain weather elements, like clouds, visibility and wind, are of particular interest to pilots.

Climate average weather extremes Q: What is the difference between weather and climate?

A Satellite’s View of the Weather geostationary satellites Atmospheric observation from satellites was an important technological development in meteorology. Other important developments include computers, internet, and Doppler radar.

Storms of all Sizes midlatitude cyclonic storms hurricanes and tropical storms thunderstorms tornadoes Storms are very exciting, but they also play an important role in moving heat and moisture around throughout the atmosphere.

Figure 1.15: Doppler radar has the capacity of estimating rainfall intensity. In this composite image, the areas shaded green and blue indicate where light-to-moderate rain is falling. Yellow indicates heavier rainfall. The red-shaded area represents the heaviest rainfall and the possibility of intense thunderstorms. Notice that a thunderstorm is approaching Chicago from the west. Fig. 1.17 Fig. 1.15

A Look at a Weather Map wind speed and direction cyclones and anticyclones fronts Wind direction is defined in the opposite way as ocean currents: a southerly current means water is moving towards the south.

a) southerly, b) northerly, c) easterly, d) westerly Figure 1.13: Simplified surface weather map that correlates with the satellite image shown in Fig. 1.12. The shaded green area represents precipitation. The numbers on the map represent air temperatures in °F. Q: What is the wind direction in Chicago? a) southerly, b) northerly, c) easterly, d) westerly Fig. 1-13, p. 17

Weather and Climate in our Lives wind chill, frostbite and hypothermia heat exhaustion and heat stroke cold spells, dry spells and heat waves severe thunderstorms and flash floods The mathematical formula for determining the wind chill temperature has recently been revised due to new experiments.

Figure 1.16: Ice storm near Oswego, New York, caused utility poles and power lines to be weighed down, forcing road closure. Fig. 1-16, p. 19

Fig. 1.19 Figure 1.18: Flooding during April, 1997, inundates Grand Forks, North Dakota, as flood waters of the Red River extend over much of the city. Fig. 1-18, p. 20