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Moisture in the Atmosphere and the Results of Energy Inputs. Created By: Mr. Kreeger. Homework and Page References. Review Book- Page 574, 579-584 Textbook-Pages 485-493 HW#1-1-3 on page 488 of textbook HW#2-1-4 on page 493
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Moisture in the Atmosphere and the Results of Energy Inputs Created By: Mr. Kreeger
Homework and Page References • Review Book- Page 574, 579-584 • Textbook-Pages 485-493 • HW#1-1-3 on page 488 of textbook • HW#2-1-4 on page 493 • HW #3-Explain why condensation is a heating process and evaporation is a cooling process, how do these processes affect storm formation
Table of Contents • Moisture and Energy Input • Air movement • Breezes and currents • Winds • Pressure Gradients • Local Breezes • Planetary Convection Cells • Planetary Winds • Jet Streams • Clouds • Formation/Rising and Subsiding air • Why they form • How are they classified • Precipitation
1. Moisture and Energy Input • Moisture in atm depends on • Evaporation-(LG) • Transpiration- Water released by plants • Evapotranspiration- All water vapor released, large amounts of energy (540cal/gm)
2. Air Movement a) Breezes and Currents- A breeze is a small local movement of air while a current is a vertical movement of air (T-Storms)
2b. Winds • A wind is a large horizontal movement of air near the Earth’s surface (named for direction from which it comes), Ex. SW wind means it came from SW and is moving NE. • Pressure gradient-The rate of change in pressure between 2 locations (ESRT), closer the isobars, stronger gradient, stronger wind, further, less gradient, less wind.
Activity on Winds • Determine which scenario world have greater winds. • HP=1025mb, LP=990mb, Dist=5km • HP=1030mb, LP=996mb, Dist=7.5km • HP=1022mb, LP=998mb, Dist=10km
2b2. Local Breezes • Day-Land heats faster than water (LP-Land, HP-Water)-Air flows from sea to land. (Sea breeze) • Night-Land cools faster than water (HP-Land, LP-Water)-Air flows from land to sea. (Land breeze)
2b3. Planetary Convection Cells (ESRT Page 14) • Convection Cell- Cyclic movement due to density difference and effects of gravity. • Variations in insolation(Why?) result in unequal heating of earth’s surface and atm. • Air moves verticallypressure belts produced • Rising air (LP)-Zones of convergence (Moist) • Sinking air (HP)-Zones of divergence (Dry)
2b4. Planetary Winds(ESRT Page 14) • If earth did not rotate and was equally heated 1 convection cell would be produced from NP to equator. • BUT>>>>> it is modified by Corilois effect which aid in creating a planetary wind system. • At equator- Wind moves due to trade winds • At mid latitudes- move due to prevailing westerlies • At high latitudes- move due to polar easterlies
2b5. Jet Streams • Winds at high altitudes that control movements of air masses. • Travel at 7-8 miles high( travels at 200 kph, travels faster in winter) • Migrates from 31N in winter to 50 N in summer Why?
3. Clouds • Formation-Condensation, need a surface called cloud condensation nuclei (CCN), can only occur when saturation happens (Dewpoint=Air Temp) and a CCN is present i.e. dust, salt • Condensation is a heating process- fuel for storms (540 cal)
Rising and Subsiding Air High P 1. RISING AIR EXPANDS AND COOLS Lower P High P Higher P Lower P Lower P 2. SUBSIDING AIR IS COMPRESSED AND WARMS Low P Higher P (surface)
3c. How are clouds classified • Divided into groups based on the height in which they form.
High Clouds • > 6000 m • Cold and “dry” - thin • Almost exclusively ice crystals Cirrocumulus halo mackerel sky mares’ tails
Middle Clouds • 2000 – 7000 m • Mostly water droplets, some ice crystals Morning Ac means afternoon thunderstorms in summer No halo, associated with warm fronts, form before storms
Low Clouds • <2000 m • Almost always water droplets (ice and snow in winter) Light-moderate rain For long duration High pressure, Stabile weather Fog that doesn’t reach the ground, drizzle
Clouds with Vertical Development • Cumulonimbus – unstable atmosphere • Rapid convection brings tops to 12 km • Form thunderstorms / lightning Fair weather Thunderstorms
4. Precipitation • When water droplets or ice crystals grow large enough to fall. • Types • Rain • Snow • Sleet • Freezing rain • Hail
Rain • Drops of water that fall from a cloud with a diameter of >0.5mm • Originates from nimbostratus or cumulonimbus clouds • Begins often as snow crystals, but also as raindrops
Snow • Packets of ice crystals • Low temps light fluffly snow or “powder” • Warm temps (-5C) heavy moist snow
Sleet • Sleet = small, translucent particles of ice • Formed as ice, melted, refrozen as ice pellets
Freezing Rain • Subfreezing air near ground is not thick enough to allow raindrops to freeze • Raindrops supercooled
Hail • Hard round pellets • Concentric shells of ice from traveling up and down a convective cloud • Produced in large cumulonimbus clouds, speeds = 160km/hr