MIDTERM STUDY GUIDE Weather instantaneous description of what the atmosphere is doing at a particular time and place Climate long term average of weather what weather is usually like in a region not just the average weather but also a description of what the extremes are like too Different hemispheres different weather WHY Because there are different ratios of land to oceans Oceans tend to act like a thermostat Mountains cause instabilities in the airflow Southern hemisphere is calmer FRONTS You will often hear TV meteorologists refer to cold and warm fronts when describing the weather Fronts are regions where cold and warm masses meet This is the region where most of the weather is generated We identify four main classes of fronts o Warm o Cold o Stationary o Occluded Each has a unique system Warm Front vs Cold Front Warm air mass flows over cold air mass Cold air mass flows under warm air mass Weather symbols LECTURE 2 Atmospheric Composition 3 most common gasses Nitrogen N2 78 Oxygen O2 21 Argon AR 93 Trace Gasses Carbon Dioxide CO2 0 038 Methane produced whenever plant material decays below water marshes and rice paddies greenhouse gas has a long lifetime in the Troposphere and breaks down in the Stratosphere to form water Ozone Chlorofluorocarbons scientific name from Freons have a long lifetime in the Troposphere but break down in the Stratosphere to release chlorine responsible for the Ozone hole Water Vapor 0 4 ATMOSPHERIC CO2 DIAGRAM Carbon Cycle Sources Volcanoes Plant animal respiration Plant decay Burning off fossil fuel Deforestation Sinks Plant photosynthesis Oceans Carbonates Hydrologic Cycle Reservoirs and Exchanges Oceans rivers glaciers lakes the atmospheric soil living tissue Exchange mechanisms evaporation condensation precipitation transpiration Cycle fueled by solar energy The Hydrologic Cycle Water is everywhere on Earth It is in the oceans glaciers rivers lakes the atmosphere soil and in living tissue All of these reservoirs constitute the hydrosphere The continuous exchange of water amongst the reservoirs is known as the hydrologic cycle It is powered by energy from the sun Particles suspended in the atmosphere Diameters measured in microns one millionth of a meter Can modify the amount of solar radiation that radiation that reaches the surface Can act as a condensation nuclei for cloud droplets Primary sources Evaporation and transpiration Precipitation Run off to the sea Aerosols o Sea salt spray o Wind erosion o Volcanoes o Fires o Human activity Atmospheric Pressure Weight of air above a certain point Important pressure changes with altitude o Pressure decreases with height TEMPERATURE and DENSITY determine the pressure 1 Troposphere literally means region where air turns over temperature usually decreases on average 6 5 C km with altitude TROPOPAUSE 2 Stratosphere layer above the troposphere little mixing occurs in the stratosphere unlike troposphere where the turbulent mixing is common 3 Mesosphere region where temperature again decreases with height STRATOPAUSE MESOPAUSE 4 Thermosphere region with very little of the atmosphere s mass High energy radiation received by the thermosphere high temperature experienced A small density of molecules not much heat would be felt Lecture 3 How Energy is transferred in the atmosphere Tornadoes hurricanes severe storms all require a large energy source All of this energy comes from the sun o Conduction mainly through land heat flow along rod Transfer of energy through matter Air is a poor conductor Only important at the Earth s surface o Convection vertically thunderstorms heat flow candle Transfer of energy by vertical movement of mass Can only take place in liquidsa Creates worldwide circulation o Advection horizontally fronts cold air advection cold warm Horizontal movement of air o Latent Heat Release vaporization of water phase changes of water Latent heat is the heat absorbed or released by unit mass of water when it changes phase o Radiation from the sun energy is transferred to the Earth from the sun by electromagnetic waves each wave is characterized by a wavelength and a frequency IMPORTANT RADIATION LAWS Wien s displacement laws wavelength of peak radiation is inversely proportional to blackbody temperature Stefan Boltzmann Law energy emitted from a warm body is proportional All things emit thermal radiation Latent Heat Heat absorbed or released by a unit mass of water when it changes phase Latent heat of melting fusion Latent of vaporization condensation Heat of sublimation deposition This gives us another way of transferring energy to the atmosphere Oceans absorb solar energy to evaporate water vapor Water Vapor transported by wind Latent heat is the source of energy that drives severe weather ex Hurricanes Why are there seasons on sunlight Earth axis tilted 23 5 degrees from the perpendicular inclination of the axis This angle changes the solar zenith angle of the sun and the area covered by a beam Larger solar zenith angle the less energy per unit area Shorter wavelengths blue and violet are scattered More effectively than longer wavelengths red and orange Lecture 4 Surface Radiation 25 penetrates directly to earth s surfaces 51 of sunlight reaches surface 26 scattered by atmosphere but then reaches the surface Reflection and Atmospheric Absorption ALBEDO the fraction of energy that is reflected by a surface is called its albedo 31 reflected back to space by clouds atmospheric scattering and reflective surface ex snow ice This is the albedo of the earth the fraction of energy reflected by the earth 19 absorbed by clouds and atmospheric gases good absorbers Significant absorbers are oxygen ozone and water vapor 50 of sunlight goes back into space Absorption Gases are excellent absorbers When radiation is absorbed energy is converted into internal molecular motion rise of temperature Significant absorbers are oxygen ozone and water vapor Latitudinal Heat Balance High albedo low albedo For the globe as a whole the amount of incoming solar radiation is equal to the outgoing terrestrial radiation thermal equilibrium But at the equator the net is positive and at the poles net is negative There is a balanced achieved by heat transport ocean currents ex The Gulf Currents and the atmospheric transfer of heat THE GREENHOUSE EFFECT Lecture 5 Air Temperature Data Daily mean temperature is determined by two methods A Average of 24 hourly measurements B The average of the maximum and minimum temperatures for