GEOG 203 Exam 2 Study Guide Chapter 7 Water and Atmospheric Moisture Reviewing Atmospheric Circulation Latitudinal variation in incoming energy o Primary driver of global atmospheric and oceanic circulation Jet streams create varying temperatures throughout the sea and control climate Local Winds Land sea breezes o Increasing temperature differences between the land and the sea forms it o Cooler air from the sea moves inland o Air temperature generally gets cooler compared to nearby locations as you move towards a large body of water Mountain valley breezes o Formed similar to land sea breezes o During the day the sun heats up the valley air rapidly and this causes it to rise creating a warm upslope breeze The opposite happens at night Oceanic Currents The driving force for currents is the frictional drag of the winds Surface currents o Because ocean currents flow over distance and through time the Coriolis force deflects them o Upwelling and downwelling flows Upwelling surface water being swept away from the coast Downwelling excess water gravitating downwards o Equatorial currents Trade winds drive the ocean surface waters westwards in a concentrated channel along the equator Deep Currents o Differences in temperature and salinity produce density differences that work to create deep currents o Density Driven Water on Earth Worldwide equilibrium Established 2 billion years ago Eustatic sea level global sea level Rate of water out gassing from earth loss of water to space Sea level is 100m higher than 18 000 years ago Sea level is 20 40cm above 100 years ago Distribution of Earth s water today Importance of Water Medium of life o 70 of our body weight o Major constituent in plants and animals o 2 3 days without water death Water covers 71 of planet s surface Water cycle nourishes planet Water movement regulates planet climate Ocean and Freshwater Distribution Ocean 97 22 of the water on earth Freshwater 2 78 o Surface water 77 78 Ice and glaciers 99 357 Freshwater lakes 0 33 Saline lakes 0 28 Atmosphere 0 03 Rivers and streams 0 003 o Groundwater 11 02 o Deep groundwater 11 02 o Soil moisture 0 18 Water Molecule Strong covalent bonds between one hydrogen H and two oxygen O atoms Dipolar 2 charges Weaker but Important hydrogen bonds Hydrogen Bonding Polarity o Small negative charge O o Small positive charge H Hydrogen bonds result from attraction Causes o High water surface tension o High solubility of chemical compounds in water universal solvent o Unusual heat properties of water o Unusual density of water Water as Solvent Water molecules stick to other polar molecules Electrostatic attraction produces an ionic bond Water can dissolve almost anything Hydration Heat Energy of moving molecules Calorie is the amount of heat needed to raise the temperature of 1g of water by 1 degree C Temperature is a measurement of average kinetic energy Water s Heat Capacity and Specific Heat Heat capacity amount of heat required to raise the temperature of 1 gram of any substance by 1 degree C Water has a high heat capacity can take in or lose much heat without changing temperature Specific heat heat capacity per unit mass o Land has a lower specific heat than water Unique Properties of Water Three states of matter water vapor water liquid ice Phase changes Water has high latent heats o Freezing melting 80 cal g o Vaporization condensation 540 cal g o At sea level 1cal degree C Density Properties o Maximum density reached at 4 degress C o Volume increases density increases Density of ice 0 91 density of water Water is a non compressible fluid The reason icebergs float Cloud Formation Processes Moisture droplet Cloud condensation nuclei Clouds Cloud formation processes Cloud types and Identification o Clouds are classified according to 1 Form Flat stratus stratiform Puffy cumulus cumuliform Wispy cirrus cirroform Height Low 2000m Middle 2000 6000m High 6000 13000m Vertically developed spanning multiple heights Humidity Relative Humidity o Humidity relative to total humidity that the air could hold at that temperature o Changes with temperature and pressure Specific Humidity o Mass of water vapor per total mass of air o No change with temperature or pressure Measured using a hair hygrometer or a sling psychrometer Atmospheric Stability Adiabatic processes warming or cooling rate of air parcels o Normal Lapse Rate 6 4C 1000m 3 5F 1000f o Dry Adiabatic rate Unsaturated air 10C 1000m 5 5F 1000f o Moist Adiabatic rate Saturated air 6C 1000m 3 3F 1000f o Cooling by expansion Cools internally as it expands under lower air pressure o Heating by compression Heats internally as it is compresses by higher air pressure Stable and unstable atmospheric conditions Stability tendency of an air parcel to remain in place or to NOT change position rise fall Parcel is stable if o Resists upward movement and or sinks backs into its starting point Parcel is unstable if o Continues to rise freely on its own Need to know the TEMPERATURE Fog Clouds that are in contact with the ground Advection fog o When air in one places migrates to another place where conditions are right for saturation Evaporation fog o Form of advection fog o Cold air lies over warm water of a lake or ocean surface Valley fog o Advection fog o Cool air is denser than warm air it settles in low lying areas producing a fog in the chilled saturated layer near the ground in the valley Radiation fog o When radiative cooling of a surface chills the air layer directly above that surface to the dew point temperature creating saturated conditions Chapter 8 Weather Air Masses Classification o Humidity M maritime moist C continental dry o Temperature A Arctic P Polar T tropical E equatorial AA Antarctic Air Masses affecting North America o cP dry cool stable high pressure Canada Alaska o mP moist cool unstable Pacific Aleutian Low Atlantic Icelandic Low o mT humid warm o Gulf Atlantic Unstable winter to very unstable summer o Pacific Stable to conditionally unstable o cT dry low humidity hot Only in summer in USA Air Mass Modification Atmospheric Lifing Mechanism Convergent Lifing Convection Lifing Orographic Lifing o Precipitation is windward side the moisture only be held in clouds for so afer it has been o Therefore the precipitation the windward and leaves the side dry and free from rain Frontal lifing o Cold fronts Cold air forces warm air alof 400km wide 250 mi o Warm fronts Warm air moves up over cold air 1000km wide 600 mi Cold Front on the because can