EAS 1600 Midterm: EAS Study Guide Exam 2

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Georgia Institute of Technology
Earth and Atmospheric Sciences
EAS 1600

Exam 2 Study Guide Lecture 7 Convection: Heat energy is transported by motions of a fluid generated when a fluid in a gravitational field is heated from BELOW and overturns as cold fluid from ABOVE sinks and warm fluid below rises Latent Heat: heat energy released or absorbed during the transition from one phase to another Latent heat of vaporization: energy is taken up by evaporation and then released to the atmosphere during condensation • 45% of incoming sunlight is absorbed by Earth’s surface and re-radiated as IR radiation Ideal Gas Law PV = nRT - P = pressure (Pa) - V = Volume (m ) 3 - T = temperature (K) -1 -1 - R = gas constant = 8.314 JK mol - n = number of moles of gas Density  = kg/m 3 - cold air is denser than warm air Effect of latitude on radiative flux - Higher latitude, lower flux Air Movement Vertical Air Movement - Positive: air parcel is less dense than the surrounding air, so it rises - Negative: air parcel is denser than the surrounding air, so it sinks (subsides) - Neutral: air parcel is the same density, so it remains in place Horizontal Air Movement - Air moves from high to low pressure zones Troposphere - Convective (heated from bottom) - Higher temperature at bottom of troposphere, cools at altitude increases - Where most weather occurs (because convective heat drives weather patterns Stratosphere - Absorbs UV radiation by the Ozone layer, which warms it - It’s not convective, so it is heated from above. - Higher temperature at top, so it is warmer as the altitude increases Net radiation: - incoming solar radiation - outgoing terrestrial radiation - Negative Net radiation = energy deficit - Positive Net radiation = energy surplus Net radiation vs. Temperature - Negative Net radiation = temperature decrease o Less incoming radiation than outgoing radiation, so Earth must cool - Positive Net radiation = temperature increases o More incoming radiation than outgoing radiation, so Earth must warm Net radiation vs. Latitude: - Tropics (near the equator) get warmer, because of energy surplus (Positive Net Radiation) - Polar regions get colder because of energy deficit (Negative Net Radiation) To reach an energy balance, warmer air must be carried towards the poles, and colder air must be carried towards the equator Lecture 8 Air Pressure - Air pressure decreases (exponentially) as altitude increases - Air pressure changes the fastest from 0 – 10 km - Air pressure changes most rapidly in the vertical direction 0 High Pressure(divergence) zones (latitude of 30 )  drier - Pulling air down, which is dry air - Example: deserts Low Pressure(convergence) zones (latitude of 0 )  Wetter - Pulling air up, which is wet air - Example: Tropics Convergence: - Merging of air masses moving inward toward a low-pressure zone o - At the equator (0 ), this is called The Intertropical Convergence Zone (ITCZ) - During the summer solstice, the ITCZ is further north (23.5 N above the suns rays). During the winter solstice, the ITCZ is further south (23.5 S below the suns rays) Coriolis Effect: - Tendency for a fluid (air or water) moving across the earth’s surface to be deflected from its straight path - In the Northern Hemisphere, it is deflected to the right - In the Southern Hemisphere, it is deflected to the left • Coriolis Effect increases with latitude • Coriolis Effect increases as the object speed increases • No Coriolis Effect at the equator Lecture 9: • Hurricanes develop over warm water and are sustained by latent heat via a positive feedback loop • Can’t cross the equator because there is no Coriolis Effect Obliquity (Tilt) - Angle of Earth’s spinoaxis is tilted - Currently, it is 23.5 - Hemisphere that is tilted towards the sun received MORE solar energy Seasons are controlled by obliquity: - March Equinox (March 20) - June Solstice (June 21) - September Equinox (September 22) - December Solstice (December 21) Solar flux (S) depends on the angle of incidence of radiation upon the Earth’s Surface S = Socos(q) Where q = solar zenith angle q = latitude – solar declination Solar flux decreases as latitude increases Solar Declination – Latitude when sun is directly overhead - At the equinoxes, solar declination = 0 o - June Solstice = 23.
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