UNIT 2 - ATMOSPHERE

ATMOSPHERE = LAYER OF GASES HELD CLOSE TO THE EARTH BY GRAVITY COMPOSITION: NITROGEN (N2) = 78% OXYGEN (O2) = 21% WATER VAPOR (H20) CARBON DIXOIDE (CO2) METHANE (CH4) OZONE (O3) ARGON (Ar) IT INSULATES THE EARTH’S SURFACE

AIR PRESSURE: the atmosphere is pulled down by gravity *Most of the mass of the Earth’s atmosphere is within the lower 30 km. (gets denser at surface) *measured in (hPA) = inches of mercury Weather forecasters measure air pressure with a barometer. Barometers are used to measure the current air pressure at a particular location in "inches of mercury" or in "millibars" (mb). A measurement of 29.92 inches of mercury is equivalent to 1013.25 millibars.

WEATHER VS CLIMATE WEATHER: the state of the atmosphere at a particular place at a particular time. * the physical properties of weather that are measured : (wind speed, wind direction, temperature, air pressure, humidity, precipitation) CLIMATE: the average weather conditions at a particular place over a long period of time ( over 30 years ) * EX. Phoenix climate is Hot and dry

NOAA = National Oceanic & Atmosphere Administration METEOROLOGISTS = STUDY WEATHER AND CLIMATE WHY DO WE HAVE WEATHER???? Weather results from the uneven warming of the Earth by the Sun.

CLIMATE EVIDENCE: GLACIER GAS BUBBLES TREE RINGS DEEP ICE CORE SAMPLES https://www.youtube.com/watch?v=Atp412HEHDY

LATITUDE: the distance from the equator measured in degrees North and South of equator *high latitudes *low latitudes EQUATOR = 0 degrees NOTE: The most important factor that determines climate is the distance from the Equator

SOLAR ENERGY TRANSFER:

ATMOSPHERE LAYERS

TROPOSPHERE: *Nearest to Earth’s surface ( active area) *extends to 18 km above surface ( 7 miles) *weather occurs here (has clouds) *densest layer ( makes up about 75% of atmosphere’s mass) *temperature decreases as altitude increases (to – 60 ° C) *thin layer compare to the others *lowest altitude has the warmest portion due to surface radiated heat *Tropopause is the buffer zone between the Troposphere and next layer

STRATOSPHERE *above the troposphere *20 – 50 km above surface (commercial air planes travel here) *lower part cold (-57° C) and has strong winds as part of a circulation pattern *has a thin Ozone Layer---- protects Earth from harmful UV radiation Temperature increases as altitude increases due to absorption of UV heat by Ozone layer *no major weather *stratopause: the buffer zone between stratosphere and next layer

MESOSPHERE *middle layer *extending from 80 to 90 km *coldest layer *temperatures decrease with altitude (-101° C ) *meteors burn here (shooting stars)

THERMOSPHERE *at about 100 km and above *space shuttle orbits here *also known as IONOSPHERE *temperature can reach 2000 ° C *temperature increases with altitude due to gamma rays, x-rays, & UV radiation converting atoms into IONS (called IONIZATION) *this layer reflects radiowaves which allow for long distance radio communication *the accumulation of IONS produce red and green lights known as Aurora Borealis (northern lights) and Aurora Australis (southern lights) https://www.youtube.com/watch?v=fVsONlc3OUY

AIR CIRCULATION *Air moves because of solar heating * solar energy warms the Earth *warm air rises because it is less dense *cold air sinks because it is denser than warm air *as cold air sinks, it compresses and warms *as warm air rises, it expands and cools *a vertical current forms = CONVECTION CURRENTS HIGH AND LOW PRESSURE * cool air sinking creates areas of HIGH PRESSURE--- results in fair weather * warm air rising creates area of LOW PRESSURE--- results in stormy weather https://www.youtube.com/watch?v=rjODDPznqNM

RAINSHADOW EFFECT A dry area on a mountain side because the mountain blocks the movement of wet air.

WINDS air moving as a result of uneven heating ANEMOMETER FOR WIND SPEED ---- WIND VANE FOR WIND DIRECTION *when large mass of warm moist air rise, cool air flows along Earth’s surface ---This Horizontal Airflow creates WINDS Wind flows from areas of high pressure to areas of low pressure.

CORIOLIS EFFECT https://www.youtube.com/watch?v=i2mec3vgeaI Coriolis Effect= is the deflection of moving objects viewed from a turning frame of reference Coriolis effect causes an air motion deflection path because of the Earth’s rotation. The Earth rotates faster at the Equator than it does at the poles. This is because the Earth is wider at the Equator. *Coriolis effect explains the directional prevailing winds of the Earth

PREVAILING WINDS *TRADE WINDS= belts of winds between the equator and 30° N and S latitudes. *blow from Northeast in N. Hemisphere *blow from Southeast in S. Hemisphere *WESTERLIES= belts of winds between 30° and 60° *blow from Southwest in N. Hemisphere *blow from Northwest in S. Hemisphere *EASTERLIES= belts of winds between 60° and poles. *blow from Northeast in North Pole *blow from Southeast in South Pole

HORSE LATITUDES AND DOLDRUMS HORSE LATITUDES= a belt of calm air and sea occurring in both the northern and southern hemispheres between the trade winds and the westerlies. (30° TO 35° N & S of equator) DOLDRUMS=“equatorial belt of calms”, area around the earth centered slightly north of the equator between the two belts of trade winds. (5°N TO 5° S )

CIRCULATION CELLS HADLEY CELLS: Ferrel cell FERREL CELLS: mid-latitude cells POLAR CELLS: at pole regions

JET STREAMS = high stream currents in upper troposphere https://www Jet streams are long, narrow current of fast moving air found in the upper atmospheric levels. They are found between 10 to 14 km high in the troposphere. They blow from west to east at speeds of 240 km/h and can dip northward or southward depending on atmospheric conditions. Air temperature differences drive the jet stream.

OCEAN CURRENTS AFFECT THE ATMOSPHERE

HURRICANES https://www.youtube.com/watch?v=5iN352idLks *Hurricanes begin over warm oceans where trade winds meet and warm up *Thunderstorms form and move in a circular motion which makes it pick up moisture and heat energy. *The eye (center) is where there is descending air and low pressure. *Wind circles around the eye counter clockwise in the N. Hemisphere– it will circle clockwise in the S. Hemisphere NOTE: Typhoons are hurricane over the Northwest Pacific Ocean

HURRICANE CATEGORIES https://www.youtube.com/watch?v=nIWz60XMliE

TORNADOES https://www.youtube.com/watch?v=7bHSS1ImFQI *Tornadoes form when speeding cold fronts smash into warm humid air forming a convection of temperature and winds *Winds in tornadoes can reach speeds of over 250 km/h *the center of the tornado has low pressure *Tornadoes are unpredicatable

Please study these power point notes for your Unit 2 Exam on Monday. Note: El Nino and La Nina phenomena will not be included on this test.