Class #1: Introduction, Energy Chapters 1 and 2 1Class #1 July 7, 2010

The Earth and Its Atmosphere Chapter 1 2Class #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. 3Class #1 July 7, 2010

Overview of the Earth’s Atmosphere Composition – 99% of the atmosphere is within 30km of the Earth’s surface – N 2 78% and O 2 21% – The percentages represent a constant amount of gas but cycles of destruction and production are constantly maintaining this amount. 4Class #1 July 7, 2010

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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. 6Class #1 July 7, 2010

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Overview of the Earth’s Atmosphere Special Topic: A Breath of Fresh Air – 1 breath of air = molecules – stars in the universe 10Class #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 CO 2 and H 2 O from the cooling center of the Earth causing rain and eventually lakes and oceans. – Lakes and oceans acted as a sink, absorbing CO 2 from atmosphere. – Plants evolved producing oxygen to form our current atmosphere several 100 million ybp. 11Class #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/in 2. – Standard sea level pressure is mb = hPa = in Hg – Atmospheric pressure decreases with an increase in height. 12Class #1 July 7, 2010

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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 15Class #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 16Class #1 July 7, 2010

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Vertical Structure of the Atmosphere Special Topic: The Atmospheres of Other Planets – Each planet’s atmosphere is unique in terms of temperature and composition. 18Class #1 July 7, 2010

Vertical Structure of the Atmosphere Observation: Radiosonde – Weather balloon – Instrument and transmitter – Air temperature, humidity, pressure 19Class #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. 20Class #1 July 7, 2010

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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 23Class #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 24Class #1 July 7, 2010

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Weather & Climate Satellite’s View – Geostationary satellite – Meridians measure longitude (W-E) – Parallels measure latitude (N-S) – Weather maps: pressure cells, fronts, surface stations 26Class #1 July 7, 2010

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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 28Class #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 29Class #1 July 7, 2010

Energy: Warming the earth and Atmosphere Chapter 2 30Class #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 31Class #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 32Class #1 July 7, 2010

Temperature Scales Fahrenheit: 32 freeze, 212 boil Celsius: 0 freeze, 100 boil Kelvin: absolute; 0K = -273°C 33Class #1 July 7, 2010

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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 35Class #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) 36Class #1 July 7, 2010

Fig. 2-3, p Class #1 July 7, 2010

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 38Class #1 July 7, 2010

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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. 40Class #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 41Class #1 July 7, 2010

Table 2-1, p Class #1 July 7, 2010

Table 2-2, p Class #1 July 7, 2010

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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. 45Class #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). 46Class #1 July 7, 2010

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Fig. 2-9, p Class #1 July 7, 2010

Fig. 2-10, p Class #1 July 7, 2010

Fig. 3, p Class #1 July 7, 2010

Fig. 4, p Class #1 July 7, 2010

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Radiation Radiation of the Sun and Earth – Sun 6000k emits radiation, electromagnetic spectrum – Shortwave radiation (high energy) from the Sun – Longwave radiation (low energy) from the Earth 53Class #1 July 7, 2010

Radiation Environmental Issue: Sunburn – UV index is a weather forecast product that indicates the potential for sun burn due to high energy or short wavelengths emitted by the sun. 54Class #1 July 7, 2010

Balancing Act If the Earth is radiating energy all the time, why is it not very cold? – Radiative equilibrium Absorb > emit = warm Emit > absorb = cool 55Class #1 July 7, 2010

Selective Absorbers Good absorbers are good emitters at a particular wavelength and vice versa. Greenhouse effect: the atmosphere selectively absorbs infrared radiation from the Earth’s surface but acts as a window and transmits shortwave radiation 56Class #1 July 7, 2010

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Fig. 2-12, p Class #1 July 7, 2010

Fig. 2-12, p Class #1 July 7, 2010

Fig. 2-12, p Class #1 July 7, 2010

Greenhouse Enhancement Global warming is occurring due to an increase in greenhouse gases – Carbon dioxide – Methane – Nitrogen Oxide – Chlorofluorocarbons Positive feedbacks continue the warming trend. Negative feedbacks decrease warming. 61Class #1 July 7, 2010

Incoming Solar Radiation Conduction, convection, and infrared radiation warm the atmosphere from below, not sunlight or insolation from above. – Scattering – Reflection, albedo 62Class #1 July 7, 2010

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Incoming Solar Radiation Observation: Blue skies, red skies, and white clouds – Selective scattering of incoming solar radiation causes reflectance in portion of the electromagnetic spectrum that correspond with the colors our eyes detect. 65Class #1 July 7, 2010

Annual Energy Balance 50% of insolation reaches the Earth’s surface. Earth absorbs 147 units, radiates 117 units, 30 unit surplus, warm. Atmosphere absorbs 130 units, radiates 160 units, 30 unit deficit, cool. Tropics have a surplus of energy. 66Class #1 July 7, 2010

Table 2-3, p Class #1 July 7, 2010

Fig. 2-16, p Class #1 July 7, 2010

Fig. 2-17, p Class #1 July 7, 2010

Stepped Art Fig. 2-17, p Class #1 July 7, 2010