Atmospheric Pressure, Wind, and Temperature Changes in Earth's Climate System - Prof. Just, Study notes of Geography

Download Atmospheric Pressure, Wind, and Temperature Changes in Earth's Climate System - Prof. Just and more Study notes Geography in PDF only on Docsity! 1 September 24, 2010 Variations by Lat. 1. Angle of incidence: Angle at which rays hit earth surface 2. Atmos. Obstruction: Insulation blocked by atmos. Particles 3. Day length: longer days = more insulation Land-water contrasts  Earth heats primarily because air above it  Land v. water is great contrast o Land heats and cools more readily o Land temps have a large range o Transmission : Land is opaque, water is not o Specific heat : Water has higher o Mobility : water is mobile o Evaporation cooling : Moisture availability Dallas average annual temp: 65 deg. F San Diego 63 deg F Heat transfer  ATMOSPHERIC CIRCULATION  Ocean circulation  Without poles would get colder and tropics more warmer  CA 75-80% of heat transfers from air circulation  Ocean currents transfer could water to low lats and warm water to higher lats. Vertical temp. patterns  Temp. change in troposphere is predictable  Decrease with increased altitude  Average change is: 3.6 deg F/1000 ft (6.5 deg C/1000m) Inversions  exceptions to the rule  radiation inversion o clear winter night, ground cools by loss of long-wave rad. Cools air by conduction  Advection inversion o Cold air brought in by wind (horizontal) 2  Cold-air-drainage o Cold air moves down slopes at night  Air quality implications Major controls of temp.  Latitude  Land water contrasts  Atmospheric circulation  Ocean currents  Altitude Sept 27, 2010 Global warming  Natural greenhouse effect  Data indicate earth climate is getting warmer  What is that cause?  CO2 and others  Increase > 40% since 1750  Highest in 650,000 years  **Industrial Revolution cause the biggest increase Pressure and wind Pressure  The unrecognized element  Tied to other weather element  Pressure and wind are closely connected Impact  Pressure has a significant, but indirect impact on earth  Influence manifested by wind and temp  Wind is more easily recognized (visual) Nature of pressure  Gas particles are loosely bound o Unlike solids or liquids  Continues motion of particles 5 Isobars- high and low are relative Wind  Horizontal movement of air The event  Unequal heating of earth > temp gradients > generate pressure gradients > air moves from high to low pressure from high to low Air moves from LEFT to RIGHT on gradient With rotation  The coriolis effect (force) o Bent right in North Hemisphere o Bent left in South Hemisphere Friction (force)  The drag of air moving across earth’s surface  Reduces wind speed o Weakens coriolis  Greatest at earth surface and diminishes with altitude  Friction layer: extends ca. 3500 ft. above earth 3 forces 1. Pressure gradient 2. Coriolis 3. Friction 4. Relationship between these influences air movement Movement upper atmos.  Pressure = coriolis  Movement parallel to isobars (geostrophic wind)  Circulates clockwise around HI and counter clockwise around LO (H hemi.) Low atmo.  Friction slows wind, so less coriolis  Pressure > coriolis  Movement is from HI to LO, but bent with coriolis Circulation patterns 6  Predictable patterns of air movement around HI or LO pressure centers  8 possible movements o 4 in each hemi.  Hi and low at upper lower atmos.  Low pressure = cyclone  High pressure = anticyclone In our hemi:  Anticyclone (HI) = clockwise  Cyclone (LO)= counterclockwise Opposite in southern hemi. Movement  High pressure = descending air  Low pressure = ascending air  High pressure= clockwise  Low pressure= counter clockwise  Air moves from high to low pressure October 1, 2010 Wind Speed  Primarily a function of pressure gradient  Steep gradient = fast moving air  Gentle gradient = slow moving air  Based on closeness of isobars Wind energy  Wind farms  Steady wind of 15-20 knots  Converts 1/3 of available energy to electricity  No pollution, does not alter land use, day and night energy  Birds died because of the windmills  TVA 7 Global atmospheric circulation  Broad-scale atmospheric motion  Major semi-permanent conditions of pressure and wind  Principal mechanisms for latitudinal and longitudinal heat transfer  1/3 comes from atmospheric circulation Low pressure at the equator & High pressure at the poles (Descends at the poles) ***Basic pattern (Know the order!!)  Polar high  Polar easterlies  Polar front (subpolar low)  Westerlies  Subtropical high  Trade winds  Inter-tropical convergence zone (ITCZ) Global circulation  Closed system  No beginning or end  Driven by process we have discussed 10 October 4, 2010 Variations  Patter shifts with seasons o ITCZ  Follows the declination of the sun Monsoons  Seasonal precipitation regime  Heavy summer rains from moist air Land and sea breeze  Common along coastlines  Sea breeze = day  Land breeze = night  Diurnal pattern of heating, pressure, wind Valley and mountain breeze  Slopes heat during day  Valley flow stays cool  Slopes loose heat at night Katabatic winds  Originate in cold upland areas  Move to lower elevations under gravity  Sometimes channeled in valleys o Can be destructive Chinook winds  Common in high relief areas  Steep pressure gradient on opposite sides of topographic barrier  Rapid descent down leeward slope Santa Ana Winds  High pressure over the interior of the US  Wind diverges clockwise  Brings hot, dry air to coastal California  Should be moist, warm air from Pacific  Ideal conditions for wildfires 11 October 8 Moisture > Temp pressure wind moisture Atmospheric moisture  Conservation  3 phases  Closed system (no imputs/outputs; same amount of water as years ago)  Most water occurs as vapor  Life is not possible without water Nature of water  Most widespread substance on earth surface (70% of earth)  No measurable characteristics  Pure water is odorless, tasteless and colorless  Good solvent  Higest density at 4 deg. C (ice floats) Water molecule  Atoms are building blocks of matter  2 or more atoms together is a molecule  2 H & I0 (H20)  -> covalent bonds hold H & O  H are on same side  Separated by 105 degrees o Electricity polarity o H side is positive, O side is negative  Allows from Hydrogen bonding – water molecule to water molecule  (H2O+OH2O= hydrogen bond) Properties Density  Most substances contract as temp drops  Water only goes this to 4 deg C then it expands  Expands until it reaches freezing  Solid water is less dense then liquid (ice floats) 12 Surface tension Strong hydrogen’s  Cohesion- water sticks to water  Adhesion- Water sticks to objects Universal solvent  Most substances dissolve in water polarity  Attracted to over chemical compounds  Water in nature is always impure  Also carries solid particles Specific heat Increased temp of 1 gram by 1 deg. C High specific heat (land/water contrasts) Phase change  Evaporation : liquid gas( energy is stored think of sweat)  Condensation : gas to liquid  Sublimation: solid to gas or gas to solid  Freezing: liquid to solid  Melting: solid to liquid Each change stores or releases energy Latent heat  Energy is stored or released  Released: temp increases  Absorbed: temp decreases  Evaporation= absorbed= cooling Absorbed = cooling Ice in tray for wks, gas comes out when you open freezer Importance of latent heat Atmospheric science is largely  Condensation  Evaporation 15 RH=SH/CAP RH=100% SH=CAP From large to small (figure) 1. Typical raindrop (biggest) 2. Large cloud 3. Large droplet 4. Typical cloud droplet 5. Typical condensations nucleus (smallest) Water is sticky (cohesive) Adiabatic processes  Heating by compression  Cooling by expansion  Important in physical geography  Rising/falling air cools/warms at predictable rates o Dry adiabatic rat o Saturated adiabatic rate Rates  Dry adiabatic rate (DAR): o Air not saturated (SH<CAP) o 10 deg. C/1000m or 5.5 deg. F/1000 ft  Saturated adiabatic rate (SAR): o Air is saturated (SH=CAP) o 6 deg. C/1000 m or 3.3 deg. F/1000 ft  Still cools but to a lesser degree because latent heat rel.  Air warms at the dry adiabatic rate Figure- X axis is Temp, Y axis is altitude, at dashed line DP temp is met. SH=CAP Adiabatic verses Lapse Rates  Adiabatic is dynamic air (moving)  Lapse rate is static (non-moving)  DAR (10 deg. C/1000 m or 5.5 deg. F/1000 ft)  SAR (6 deg. C/1000 m or 3.3 deg F/1000 ft)  ELR (6.5 deg C/1000 m or 3.6 deg F/1000 ft) 16 Clouds  Concentrations of water droplets and/or ice crystals October 25, 2010 EXAM 2  Information since exam 1  Chapter 3  Chapter 4 (first half, to ocean currents)  Chapter 4 (first half, thru air masses) Global temperature  Global patterns and processes  Latitude  Land-water contrasts  Atmospheric circulation  Ocean circulation  Altitude  Global warming Pressure  Density, temp, and pressure  High v. low (how its measured)  Thermal (temp driven) v. dynamic (movement driven)  Measurement Wind  Pressure gradient, Coriolis and friction  Movement o High and low pressure o Upper and lower atmosphere o North and south hemi o Vertical component  Global pressure and wind patterns  Variations (e.g. land-sea breezes) 17 Moisture  Properties of water  Phase change  Hydrologic cycle (i.e. processes)  Adiabatic processes  Adiabatic and lapse rates Moisture  Clouds  Fog -know the 4 types of fog  Dew- know lifting condensation  Precipitation  Spatial and temporal patterns – know places on earth why it’s wet or dry and why and why they will change  Variability- know why it changes from one place to another  Acid rain- understand what acid precept is and why we have an impact on it Know the total 10 cloud types and which produce rain Air masses  Definitions (3)  Know the codes o mT, cP, A  Know the frontal symbols  Understand weather maps In book see all codes and what they mean