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Weather and Climatology


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Characteristics of the troposphere
1st layer troposphere: The bottom layer, the \"weather layer. Reasons 1. vertical mixing. 2. water vapor content
characteristics of the stratosphere
2nd layer. contains the ozone layer. little mixing: pollutants may persist there for months to years. No weather: good for smooth flying. It warms because of: -the interaction of ozone and ultraviolet light -the injection of moisture by meteors -dust and dirt deposited by volcanoes -the injection of moisture by high-flying aircraft -global warming
dew point temperature
dew point is the temperature to which air needs to be cooled to reach saturation. in other words, it\'s the temperature when air becomes too condense and dew forms.
mechanisms of heat transfer
convection- heat transferred by ass movement or circulation of a fluid. responsible for the redistribution of heat between hot equatorial regions and the frigid poles. radation: how the sun heats the heart. heat- transfer mechanism
rain shadow deserts; reasons for their formation
by the time the air reaches the leeward side of a mountain, much of its moisture has been lost. if the air descends, it warms adiabatically, making condensation and precipitation even less likely. Result-rain shadow desert
what can enhance the instability of the atmosphere?
1. intense solar heating warming the lowermost layer of the atmosphere 2. the heating of an air mass from below as it passes over a warm surface 3. general upward movement of air caused by processes such orographic lifting, frontal wedging, and convergence 4. radiation cooling from cloud tops
Factors that affect the precipitation intensity in a city
1. more buildings->greater friction->convergence 2. pollutants, particulate matter (fine particles)->CCN 3. heat island effect->instability
how do pressure gradient force, the coriolis force, and the friction influence wind?
The coriolis force: caused by earth\'s rotation. -it always acts to deflect an object to the right of its direction in the northern hemisphere -magnitude zero at the equator, maximum at the poles -the coriolis force is larger for parcels moving at faster speeds, it\'s zero if a parcel is not moving -it affects only wind direction, NOT speed Friction: -only acts at the surface -acts to slow down air movement. direction opposite to air -faster the wind blows, stronger the friction is -negligible above a height of a few kilometers
the movements of air associated with the two types of air pressure centers; low (cyclones) and highs (anticyclones)
high pressure- move clockwise; away from the center low pressure- move counterclockwise; toward the center
subtropical highs; how they affect the climate
-located in the belts around 20-35 degrees latitude -downward air flow...subsiding air (adiabatic heating) and divergent winds at the surface- warm, cloud-free weather -many large deserts are located along this latitudinal belt
mid latitude cyclone features
comma shaped air mass that goes counterclockwise in the northern hemisphere and is a low-pressure system
mid latitude cyclone development
development: warm air advances poleward invading the area formerly occupoed by cold air, while cold air moves equator ward occlusion: the position of the cold front advances faster than the warm front and begins to close (lift) the warm front
air-mass thunderstorms: features and occurence
features: 1. lightning and thunder 2. heavy rainfall 3. cumulonimbus-vertically developed 4. wind-gusty (severe) 5. hail (severe) occurence: produce in the summer, typically in the afternoon, because surface temperatures are highest, therefore there is unstable air
air mass thunderstorms three stages of development
first stage- cumulus growth stage -a cumulus cloud begins to grow vertically -air within the cloud is dominated by updraft -usually no precipitation and lightning during this stage second stage- updrafts and downdrafts -most dangerous (winds, thunder, lightning, hail, etc.) third stage-dissipation -downdrafts only which cut off fuel energy for cyclone -light precipitation -eventually, cyclone dies
severe thunderstorms: features
classified as severe when: 1. winds exceed 58 mph OR 2. produces hailstones>.75 inch OR 3. produces tornado
severe thunderstorms occurrence (when and where; why)
summertime afternoon because of warm, unstable air. most often in the Great Plains because the warm (unstable) air is dry and shallow and the ice crystals do not have time to melt
lightning and thunder
lightning: an electrical discharge-a giant spark thunder-when lightning strikes, intense heat expands the air in and around it so rapidly that it results in loud noise known as thunder. explosion
tornado features
-tornadoes (twisters, cyclones) are violent windstorms that take the form of a fast rotating column of air -tornadoes extend downward from a cumulonimbus cloud -the pressure at the center of a tornado is as much as 10 percent lower than immediate outside of the storm
tornado occurence (when and where; why)
occurs most in may (spring) in great plains. 1.warm, moist surface air fromt he maritime tropical air mass..cp and mt collide in Great plains 2. cooler and drier air aloft. together, 1 and 2 create a very unstable atmosphere
Hurricanes occurence (when and where; why)
tropical oceans in 5 to 20 degrees latitude. hit the gulf and the atlantic but seldom the pacific. because water in pacific is colder, temperature seldom exceeds 80 degrees farenheit. winds carry away from West coast-east to west prevailing winds in the tropics
Three basic conditions for hurricane formation
1. warm temperature (above 80 degrees farenheit) 2. enough humidity (over the ocean) 3. wind pattern spinning inward (surface lows)
cloud cover/albedo control of temp and how it affects the temperature
cooling effects of clouds: -clouds have high albedo -they reduce the amount of incoming solar radiation during the day -temperature is colder on a cloudy day than on a clear day warming effect: -clouds absorb outgoing earth radiation -clouds also emit heat -temperature\'s warmer on cloudy night than a clear night
latitude control of temp and how it affects temperature
fundamental control on temperature. different latitudes receive different amount of solar radiation->responsible for warm temperatures in the tropics and colder temperatures poleward
differential heating of land and water and its control of temp and how it affects temperature
because land heats and cools faster than water, continental locations have a a larger seasonal temperature range than maritime locations. maritime locations often have more precipitation because of their proximity to a large moisture source.
ocean current control of temperature and how it affects the temperature
-the ocean exchanges heat with the overlying atmosphere -the water in the oceans and air in Earth\'s atmosphere are constantly moving, circulating cool or warm water around the Earth -it also influences evaporation rates (which are generally higher where sea-surface temperature is higher).
altitude control on temperature
temperature normally decreases with altitude
geographic location control on temperature
Proximity to a large body of water isn\'t enough. Prevailing winds determine which body influences the local climate. for example: coastal or not
three basic forms of clouds
cirrus: high, white, thin, feathery cumulus: cauliflower-life, flat base stratus: no distinct individual cloud units, covering much or all of the sky
Cirrus (high clouds)
-Cirrus clouds are thin, wispy clouds blown by high winds into long streamers. -They are almost always comprised of ice (why?) -They are considered \"high clouds\" forming above 6000 m (20,000 ft). -Cirrus clouds usually move across the sky from west to east (why?). They generally mean fair to pleasant weather.
altostratus (middle clouds)
-grayish/blue-gray thin layer covering entire sky uniformly found ahead of storms -can seen the sun through altostratus, but no halo will be observed
nimbostratus low cloud
Nimbostratus Clouds - -darker gray, \"wet\" looking low clouds -One of the chief precipitation producers. -They produce light/moderate precipitation of long duration over a large region
cumulus- low weather fair clouds
Cauliflower-like, flat bases, and distinct outlines Given suitable conditions, however, they can later develop into towering cumulonimbus clouds associated with powerful thunderstorms.
extend up to the top of the troposphere contain both water and ice produce severe weather (thunderstorms, lightning, hail, tornadoes⬦) form a distinctive \"anvil\" cloud at the top of the storm
differences between cold front and warm fronts: definitions; effects; and weather related
cold front: -cold air replaces warm air -heavy rain -vertically developed clouds -temp decreases after, NW wind warm front:-warm air replaces cold -moderate to light rain -stratus clouds -temp increases after, SW wind
Hurricane features
Tropical cyclones are low pressure systems that have thunderstorm activity and rotate counterclockwise. when winds exceed 74 mph, it is considered a hurricane Hurricane Eye: Center of the storm About 12 miles in diameter Precipitation ceases Winds subside Eye wall: Greatest wind speeds Heaviest precipitation right side of hurricane most dangerous

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