200 likes | 208 Views
Explore the essential components and layers of Earth's atmosphere, the role of solar radiation, greenhouse gases, and the impact on climate change. Discover the importance of energy balance, greenhouse effects, and atmospheric absorption. Learn about the unequal distribution of radiation and its effects on Earth's climate patterns.
E N D
Radiation and Earth’s Atmosphere www.assignmentpoint.com
Radiation and Earth’s Atmosphere • The earth’s global average surface temperature in present climate is 15C (59F). Without the atmosphere, it would be -18C (-0.4F), • About 33C or 59.4F colder! Atmosphere is the most important component of the earth’s climate. • Radiation vs. other heat sources: • Total energy enter the earth’s atmosphere: 174 petawatts or 174X1015 Watts • Solar: 99.978%, Geothermal: 0.013%, waste and fossil fuel: 0.007%, tidal: 0.002% www.assignmentpoint.com
Earth’s Atmosphere 1. What is it? A thin gaseous envelope around the planet. Blue sky! 2. Composition • Today’s atmosphere: nitrogen (78%), oxygen (21%), other (1%) – trace gases! Nitrogen, oxygen, argon, water vapor, carbon dioxide, methane, and most other gases are invisible. Clouds are not gas, but condensed vapor in the form of liquid droplets or ice particles. Ground based smog, which is visible, contains reactants of nitrogen and ozone. Four layers: 3. Structure Troposphere (overturning) From surface to 8-18 km Stratosphere (stratified) From troposphere top to 50 km Mesosphere Thermosphere www.assignmentpoint.com
The Structure of Earth’s Atmosphere 1. Four layers defined by temperature Troposphere: T decreases with elevation T increases with elevation Stratosphere: Mesosphere: T decreases with elevation Thermosphere: T increases with elevation 2. Importance to climate and climate change • Troposphere: 80% of Earth’s gases Most of Earth’s weather happens Most of the measurements • Stratosphere: 19.9% of Earth’s gases Ozone layer: Blocking Sun’s ultraviolet radiation www.assignmentpoint.com
Energy from the Sun 1. Characteristics Travels through space (vacuum) in a speed of light In the form of waves: Electromagnetic waves (Photons) In stream of particles Releases heat when absorbed 2. Electromagnetic spectrum From short wavelength, high energy, gamma rays to long wavelength, low energy, radio waves 3. Importance to climate and climate change Primary driving force of Earth’s climate engine Ultraviolet, Visible, Infrared www.assignmentpoint.com
Sun’s Electromagnetic Spectrum Solar radiation has peak intensities in the shorter wavelengths, dominant in the region we know as visible, thus shortwave radiation www.assignmentpoint.com
Blackbody Radiation Curves Any object above absolute zero radiates heat, as proportional to T4 Higher temperature, shorter wavelength www.assignmentpoint.com
Longwave & Shortwave Radiation The hot sun radiates at shorter wavelengths that carry more energy, and the fraction absorbed by the cooler earth is then re-radiated at longer wavelengths. www.assignmentpoint.com
Atmospheric Greenhouse Effects T= 15°C (59°F) Surface Temperature With the Atmosphere T= –18°C (0°F) Surface Temperature Without the Atmosphere Greenhouse effects make Earth’s surface warmer! www.assignmentpoint.com
Greenhouse Gases • What are they? Water vapor (H2O) Carbon dioxide (CO2) Methane (CH4) • Water vapor accounts for 60% of the atmospheric greenhouse effect, CO2 26%, and the remaining greenhouse gases 14%. Chlorofluorocarbons (CFC’s) Ozone (O3) Nitrous oxide (N2O) • CO2 contributes most (55-60%) to the anthropogenic greenhouse effect, and methane is a distant second (16%). • CFCs cause the strongest greenhouse warming on a molecule-for-molecule basis. www.assignmentpoint.com
Nitrous Oxide Atmospheric Absorption Methane Solar radiation passes rather freely through Earth's atmosphere. Earth emits longwave energy, which either leaks through a narrow window or is absorbed by greenhouse gases and radiated back to Earth. Ozone Absorption (100%) Water Vapor Carbon Dioxide UV IR Total Atmo www.assignmentpoint.com Wavelength
Solar Intensity and Latitude Solar intensity, defined as the energy per area, is different at different latitude. A sunlight beam that strikes at an angle is spread across a greater surface area, and is a less intense heat source than a beam impinging directly. www.assignmentpoint.com
Unequal Radiation on a Sphere Insolation is stronger in the tropics (low latitudes) than in in the polar regions (high latitudes). www.assignmentpoint.com
Pole-to-Equator Heating Imbalances www.assignmentpoint.com
What controls the elevation of the Sun above the horizon? Earth’s Tilt Primarily Determines Season www.assignmentpoint.com
Earth's Annual Energy Balance The balance is achieved locally at only two lines of latitude. A global balance is maintained by excess heat from the equatorial region transferring toward the poles. Incoming Solar Radiation Outgoing Longwave Radiation Unequal heating of tropics and poles www.assignmentpoint.com
The Global Energy Budget: Driver of Atmospheric Motion A balance exists between the incoming solar and outgoing longwave energy averaged over the globe and the year However, the tilt of the Earth means this balance is not maintained for each latitude SURPLUS DEFICIT www.assignmentpoint.com
Questions: • What is the current global mean surface temperature? • Why it is 33C or 59F warmer than it would be without the atmosphere? • Why is climate dominated by the radiation balance of the atmosphere? • What are the main greenhouse gases in the earth’s atmosphere? • In what latitudes the earth’s gain and lost radiative energy (heat), respectively? www.assignmentpoint.com
Questions: • What is the current global mean surface temperature? • 15C or 59F • Why it is 33C or 59F warmer than it would be without the atmosphere? • Because of greenhouse effect of the atmosphere • Why is climate dominated by the radiation balance of the atmosphere? • It contributes to 99.978% of total heat flux into the atmosphere • What are the main greenhouse gases in the earth’s atmosphere? • H2O, CO2, CH4, O3, CFCs, NO2 • In what latitudes the earth’s gain and lost radiative energy (heat), respectively? • Gain heat in the tropics or 40S-40N, loss heat in high latitudes (50S-50N) www.assignmentpoint.com