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Class #1: Introduction, Energy. Chapters 1 and 2. The Earth and Its Atmosphere. Chapter 1. Overview of the Earth’s Atmosphere. The atmosphere is a delicate life giving blanket of air surrounding the Earth. Without the atmosphere the Earth would not have lakes or oceans.
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Class #1: Introduction, Energy Chapters 1 and 2 Class #1 July 7, 2010
The Earth and Its Atmosphere Chapter 1 Class #1 July 7, 2010
Overview of the Earth’s Atmosphere • The atmosphere is a delicate life giving blanket of air surrounding the Earth. • Without the atmosphere the Earth would not have lakes or oceans. • Radiant energy from the sun energizes the atmosphere driving day to day weather. Class #1 July 7, 2010
Overview of the Earth’s Atmosphere • Composition • 99% of the atmosphere is within 30km of the Earth’s surface • N2 78% and O2 21% • The percentages represent a constant amount of gas but cycles of destruction and production are constantly maintaining this amount. Class #1 July 7, 2010
Overview of the Earth’s Atmosphere • Composition • Water a variable gas following the hydrologic cycle. • Carbon dioxide has risen in recent years and is an important greenhouse gas. • Other greenhouse gases exist beyond carbon dioxide. Class #1 July 7, 2010
Overview of the Earth’s Atmosphere • Special Topic: A Breath of Fresh Air • 1 breath of air = 1022 molecules • 1022 stars in the universe Class #1 July 7, 2010
Overview of the Earth’s Atmosphere • The Early Atmosphere • The Earth’s first atmosphere was composed mostly of hydrogen and helium. • The atmosphere evolved due to outgassing of CO2 and H2O from the cooling center of the Earth causing rain and eventually lakes and oceans. • Lakes and oceans acted as a sink, absorbing CO2 from atmosphere. • Plants evolved producing oxygen to form our current atmosphere several 100 million ybp. Class #1 July 7, 2010
Vertical Structure of the Atmosphere • Air Pressure and Air Density • Weight = mass x gravity • Density = mass/volume • Pressure = force/area • At the Earth’s surface the pressure of the atmosphere is 14.7 lbs/in2 . • Standard sea level pressure is1013.25 mb = 1013.25 hPa = 29.92 in Hg • Atmospheric pressure decreases with an increase in height. Class #1 July 7, 2010
Vertical Structure of the Atmosphere • Layers of the Atmosphere • Lapse rate = change in temperature with a change in height • Isothermal environment = no change in temperature with height • Inversion layer = change in the sign of the lapse rate Class #1 July 7, 2010
Vertical Structure of the Atmosphere • Layers of the Atmosphere • Troposphere: decrease in temperature, day to day weather, tropopause • Stratosphere: increase in temperature, ozone, stratopause • Mesosphere: decrease in temperature, mesopause • Thermosphere: increase in temperature, suns strongest radiation Class #1 July 7, 2010
Vertical Structure of the Atmosphere • Special Topic: The Atmospheres of Other Planets • Each planet’s atmosphere is unique in terms of temperature and composition. Class #1 July 7, 2010
Vertical Structure of the Atmosphere • Observation: Radiosonde • Weather balloon • Instrument and transmitter • Air temperature, humidity, pressure Class #1 July 7, 2010
Vertical Structure of the Atmosphere • The Ionosphere • Not a true layer but an electrified region • Ions = molecule with an additional or minus an electron • Exists at the top of the atmosphere in the thermosphere • F,E,D layer • Sun light creates layers, D disappears at night and less interference with AM radio transmissions. Class #1 July 7, 2010
Weather and Climate • Weather: short term air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind • Climate: long term patterns and average weather; not just magnitude but also frequency Class #1 July 7, 2010
Weather & Climate • Meteorology • Study of the atmosphere and its phenomena • Aristotle 340 B.C. Meterologica, meteoros: high in air • 1843 telegraph • 1920s air masses • 1940s upper air • 1950s radar and computers • 1960s satellite Class #1 July 7, 2010
Weather & Climate • Satellite’s View • Geostationary satellite • Meridians measure longitude (W-E) • Parallels measure latitude (N-S) • Weather maps: pressure cells, fronts, surface stations Class #1 July 7, 2010
Weather & Climate • Weather and Climate in Our Lives • Two general reasons for studying how weather and climate impacts our lives: economic efficiency and public safety. • Clothing • Crops • Utilities • Extreme cold and heat • Tornados and hurricanes Class #1 July 7, 2010
Weather & Climate • Special Topic: Meteorologist • Any person with a college degree in meteorology or atmospheric science; not just the TV weather person • Half of 9000 meteorologists employed by the US National Weather Service • Researchers and operational meteorologists Class #1 July 7, 2010
Energy: Warming the earth and Atmosphere Chapter 2 Class #1 July 7, 2010
Energy, Temperature, & Heat • Energy is the ability to do work (push, pull, lift) on some form of matter. • Potential energy is the potential for work (mass x gravity x height) • Kinetic energy is energy of a moving object (half of mass x velocity squared) • Temperature is the average speed of atoms and molecules Class #1 July 7, 2010
Energy, Temperature, & Heat • Which has more energy? • A lake or a cup of hot tea? • Heat is the energy in the process of being transferred from one object to another because of a difference in temperature. • Energy cannot be destroyed or created; First Law of Thermodynamics Class #1 July 7, 2010
Temperature Scales • Fahrenheit: 32 freeze, 212 boil • Celsius: 0 freeze, 100 boil • Kelvin: absolute; 0K = -273°C Class #1 July 7, 2010
Specific Heat • Heat capacity is the heat energy absorbed to raise a substance to a given temperature • Specific hear is the heat capacity divided by mass or the amount of energy required to raise one gram of a substance 1°C • High specific heat equates to slow warming and vice versa Class #1 July 7, 2010
Latent Heat • Change of state or phase change represents change between solid, gas, and liquid. • Latent heat is the energy involved in the change of state. • Ice to vapor: absorb energy, cool environment (melt, evaporation, sublimation) • Vapor to ice: release energy, heat environment (freeze, condense, deposition) Class #1 July 7, 2010
Class #1 July 7, 2010 Fig. 2-3, p. 33
Heat Transfer in the Atmosphere • Conduction: transfer heat from one molecule to another in a substance • Energy travels from hot to cold • Air a poor conductor, metal a good conductor Class #1 July 7, 2010
Heat Transfer in the Atmosphere • Special Topic: Sunbeam • Energy from sunlight on a lake can undergo many transformations and help provide the moving force for many natural and human-made processes. Class #1 July 7, 2010
Heat Transfer in the Atmosphere • Convection: transfer of heat by the mass movement of a fluid (water or air) • Convection circulation: warm air expands and rises then cools and sinks; thermal cell Class #1 July 7, 2010
Class #1 July 7, 2010 Table 2-1, p. 32
Class #1 July 7, 2010 Table 2-2, p. 34
Heat Transfer in the Atmosphere • Special Topic: Rising and Sinking • As air rises part of it s energy is lost as it expands and cools and when the air sinks it is compressed and the energy of molecules increase causing temperature to increase. Class #1 July 7, 2010
Radiation • Energy from the sun travels through the space and the atmosphere in the form of a wave (electromagnetic waves) and is called radiation. • Radiation and Temperature • All objects with a temperature greater than 0K radiate energy. • As temperature of an object increases, the more total radiation that is emitted by an object (Stefan Boltzmann Constant). Class #1 July 7, 2010
Class #1 July 7, 2010 Fig. 2-9, p. 39
Class #1 July 7, 2010 Fig. 2-10, p. 39
Class #1 July 7, 2010 Fig. 3, p. 40
