Quick study academic meteorology 600dpi

~_ _ _ _ _ _ _ _A _ CO _ _M PRE H E NSIVE G UI D E TO WEATH E R P -~ .,;.;"o _ _ _ _ _ _ THE ATMOSPHERE It was named in 1908 by Teisserence de Bort and means the region where air turns over The troposphere is the layer of the atmosphere in which most of the clouds and weather phe­ nomena occur The troposphere, in turn, has two layers The layer that touches the Earth is called the bound­ ary layer and is about to 10 miles high at the equator The troposphere's upper limit is called the tropopause and varies in height with both sea­ son and location a At the equator, the tropopause is usually about 12 miles high, and at the North Pole, about miles high b In the tropopause, the temperature of the air decreases steadily as altitude increases The rate is about -6,50 Celsius (11.7' Fahrenheit) for every kilometer (mile) you go up At the top of the tropopause, the tempera­ ture is usually about -60" Celsius A Gas Composition I The atmosphere is composed mainly of a gas known as Nitrogen , which is odorless and colorless Oxygen is the next most abundant element, with other gasses represented only in trace amounts It is interesting to note that Helium, one of these trace gasses, was discovered to exist in the sun before it was discovered on Earth a The distinctive colors that Helium emits were seen in the light coming from the sun b Scientists were able to determine what kind of ele­ ment would emit such light B Description of Composition E Stratosphere I There are several ways to describe the composi­ tion of the atmosphere: a By the weight of the constituents b By their volume (below is a list of the principle gasses in dry air, categorized by volume in the atmosphere) I The stratosphere is the layer of atmosphere that exists between the heights of 10-35 miles The temperature in the stratosphere increases with height because the ozone, which is only present in the stratosphere, absorbs ultraviolet radiation from the sun F Mesosphere PRINCIPLE GASSES OF DRY AIR Nitrogen Oxygen Argon Carbon Dioxide Neon Helium Methane Krypton Hydrogen The mesosphere is the atmosphere above the stratosphere The temperature in the mesosphere begins to fall , often reaching the coldest of any part of the atmosphere This coldest region is about 50 miles up, and can be as cold as -100°C 78.084 20.946 0.934 0.034 0.00182 0.000524 0.00015 0.000114 0.00005 G Thermosphere The thermosphere is the fourth major layer of the atmosphere It starts around 50-60 miles up Temperatures that get warmer with height char­ acterize the thermosphere H Ionosphere C Possible Origination I The Earth has what is known as a secondary atmosphere, which was created after the forma­ tion of the planet The large gas planets, Jupiter, Saturn, Uranus and Neptune, are entirely made of gas Jupiter has a primary atmosphere, which is an atmos­ phere that originated with the planet There are thought to be two possible origina­ tions of the Earth 's atmosphere: a The first hypothesized origination is by out­ gassing i When the Earth formed, it was a giant spinning ball of molten lava ii As it cooled, gasses trapped in the lava were "belched" up by large volcanoes iii The combination of these out-gassed vapors, and the biological transformation of the chemistry of the atmosphere by hundreds of millions of years of plant growth , has, it is thought, given us our con­ temporary atmosphere b The second possible origination is by cometary impact i A comet is a giant iceberg of frozen water and gasses ii If a large comet struck the Earth several billion years ago, it could have left a residue of water, carbon dioxide, oxygen and other gasses Note: The first hypothesis is now more widely accepted D Troposphere The lowest leve l of the atmosphere is known as the troposphere I The ionosphere is the layer within the thermos­ phere or stratosphere in which there are enough ionized particles to effect the transmission of radio signals Ionized particles are atoms or molecules that have more electrons than protons [negatively charged] or more protons than electrons [positively charged] The ionosphere begins about 20-30 miles above the surface It reflects longer-wavelength, lower-energy radio signals, like AM radio, back to Earth, but allows shorter-wavelength, higher-energy radio signals, like FM, to pass through into space PERCENT OF SEA-LEVEL ATMOSPHERIC PRESSURE AT SELECTED ALTITUDES Percent of Sea-Level Pressure o 3.5 10 20 30 40 50 60 100 50 10 0.1 0.01 0.001 0.00003 A The Earth's Tilt and the Seasons The Earth spins on its axis as it orbits around the Slm The axis about which it spins is tilted with respect to the plane about which it orbits the sun 3.lt is like a top spinning on a floor a TIle top does not point directly up and down as it spins b lt is inclined, in our case, at 23° with respect to straight up and down As it orbits the sun, in a near-circular path called an ellipse, it remains at the same angle and pointing in the same direction a.This tilt means that during a certain time half of the year, the top part or the Earth is pointed toward s the sun more than the lower pan b During this period, the top part receives more sun­ light than the lower part, and therefore, becomes warmer This is summer in the upper part, the Northern Hemisphere, and winter in the lower part, the Southern Hemisphere c When the Earth is on the exact opposite side of the sun, the Southern Hemisphere gets more sunlight, and it is summer in the Southern Hemisphere and winter in the Northern Hemisphere d Twice a year, the Northern and Southern Hemispheres get the same amount of sunlight I These times are called the AlIllImllal and ~ernal Equinoxes ii When it is spring in the Northern Hemi sphere it is autumn in the Southern Hemisphere, and vice versa B Eledromagnetlc Radiation I Radiation is the only mechanism of heat trans­ fer that can transmit energy across empty space The energy that powers our weather is rrom the sun Therefore, the energy that powers most, if not all , of our weather is radiative energy from the sun a The visible part of the spectrum accounts for only a small part of the radiation fi-om the sun b The vast majority of the radiative energy is invisible light in the form of radio waves, microwaves infrared waves, ultraviolet rays, x-rays, and gamma rays All of these forms of energy are the same as light, only different wavelengths The radiation from the sun takes several differ­ ent paths after it encounters the Earth as the following table summarizes: Earth % of Solar Radiation Scattered by Atmosphere into Space Reflected by Clouds into Space Reflected by Earth's Surface Absorbed by Atmosphere and Clouds Absorbed by Earth's Surface The fraction of the total radiation that is reflected by the surface of a planet is called its albedo The albedo for the Earth is 5% 22% 3% 20% 50% 30% •, C " C Heat Transfer and the Greenhouse EHect I About 50°1r, of the solar energy that strikes the Earth is absorbed by the surface The atmosphere is basically transparent to short­ wavelength, high-energy light This light passes through the atmosphere and heats the Earth a When the Earth radiates away this energy in the form of long-wavelength infrared radiation , not all of the energy escapes back into space b Some of this low-energy, long-wavelength radia­ tion is reflected back to Earth by carbon dioxide in the atmosphere This is the greenhouse effect Land heats up faster and to higher temperatures than water It also cools down quicker and to lower temperatures than water a This leads to greater temperature variations for cities away from water than for those on the coast b The body of water nearby acts as a brake, keeping the temperature from getting either too hot or too cold D Heat versus Temperature I There are important differences between heat and tem perature a Heat is the microscopic vibration of the particles that constitute an object b Temperature is a way of comparing the average energy of the particles in one ohject to the energy in another Heat is energy Temperature is relative to some specif­ ic point, such as the boiling point of water E Wind-Chili Effed I W hen air passes over water, it causes the water to evaporate a This water may be in the ocean, a lake, or on the skin's surface b When water evaporates, it absorbs energy c Since air particl es need more energy to move aro und than water particles, water must absorb energy in the form of heat when it evaporates The more water that is evaporated, the cooler the surface gets a This is how sweating keeps the body cool in the summertime Wind-thill is created when cool air moves over a surface and carries away some heat with it It sim­ ply makes the air feel cooler than it actually is F Cloud Formations I Cirrus Clouds a Cirrus cl ouds are the highe st clo uds in the atmo sph ere b.They usually exist at altitudes between 17,000 and 50,000 feet c.Al though they never actually produce rain, they often precede low-pressure systems that form many rain and snow clouds M id d le (Alto) Clouds a Mid-level clouds are called altocumulus and alto­ stratus clouds b They exist at al titudes between about 6,000 and 17,000 feet c Altocwnulus clouds are generally fluffY and white They are very common on partly sunny days d Altostratuses are grayish, uniform clouds They are never whi te They are characterized by the stratifi ed covering, which they give to the sky Low Clouds a The low clouds in the sky come in stratus, nimbo­ stratlls, stratoeumulus and cumulus vari eties b Stratus clouds are low, gray clouds that cover the sky uniform ly c Nimbostratus clouds are those stratus clouds that produce rain d Stratocumulus clouds are stratus clouds, which cover the sky unifonn!y but not produce rain Cumulus clouds are low, fluffY clouds that not produce rain Cumulonimbus a Th ese are the clouds that produce lightning stonns, hail, and tornadoes b They are produced when unstable air (which is hotter than its surroundings) is lifted into the upper atmosphere by a cold front c The warm air is cooled in the upper atmosphere, thereby producing rain d The top of the cloud may be hi gh enough to pene­ trate into the jet stream , causing the characteristic anvil-shaped top Mammatus a These are bulging, lumpy clouds sometimes seen on the underbelly of a cumulonimbus cloud b They are often associated with severe weather Orographic Clouds a This type of cloud is produced when warm air is lift­ ed by mountains into the upper, cooler atmosphere b The warm air is cooled and therefore, produces clouds and rain G Mixed Skies I In the region of a cumulonimbus cloud, many different types of clouds may be spawned, giving rise to a condition known as mixed skies , I Cold air is heavi er than warm air "'II! When a col d front is pass ing through an area, the cold air is closer to the gro und than th e warm air a Cold fronts move faster than warm fron ts, about 35 km/hr (22 mi/hr) b Cold fronts lift the warm air they are moving into, thereby cooling the r mass, and caus ing AfI clouds and rai n The rain caused by cold fronts tends to be more locali zed an d more inten se D Stationary Fronts I A stati onary front is a hot or cold front in which the airflow is parallel to the surface pos ition of the front For instance , a front can be im agined to be like a wal l a A warm front moving away fro m yo u would be slanted away fro m you and the air woul d be bl ow­ ing in the direction it is mov ing b A cold fron t moving away from you would be slanted towards you, and the air wou ld be bl owing in the direct ion it is movin g In a stat ionary tront, the w ind is bl ow ing left or righ t, not in the direction of thc wa ll, hence the tront has no motivation to move E Occluded Fronts I An occluded fron t is a situati on in which a cold front overtakes a warm front In this case, the coole r air of the cold fron t meets fro m beh ind the warm r being li fted by the cool air ahead of the warm fron t, an d com­ pl ex weather patterns often form ATMOSPHERIC PROBES & EXPERIMENTS W Balloons FRONTS A Fronts are the boundary between two air masses Warm fronts have higher temperatures and usu­ ally more moi sture than cold fronts Stable air is that which is not greatly warmer than its surroundings B Warm Fronts I Warm air is lighter than cold r When a warm front is moving through an area, the warm air is higher than the cold air Warm fronts usualJy move at about 25 km/hr (17 milhr) A warm front with stable air tends to produce light to m oderate precipi tation over an extended period for a large area The clouds often associated wiLl} these types of fronts are cirrus , altostratu s and nimbostratus Warm fronts with unstable air tend to produce heavy precipitation and cumulonimb us cl ouds C Cold Fronts A Weather BaUoons I These are the most common types of atmos­ pheric probes They often carry aloft lightweight scientific packages that measure such things as tempera­ ture, pressure, relative humidity, and altitude Balloons that transmit this information via radio signals are called radiosondes , while those that have their position tracked by radar are called rawinsondes Satellites, airplanes and rockets obtain other atmospheric information B Ancient Atmosphere I Scientists studying sedimentary rocks and ancient ice formations can explore the atmos­ phere of the past Sedimentary rocks arc those in which sediment has accumulated over time and has been compressed into rock that contains infor­ mation about atmospheric precipitates and composition Ancient ice formations may still have air bub­ bles trapped in them from many tens, hundreds or thousands of years ago, and can , th erefore be useful tools in investigating the change in the atmosphere over time I Hot air rises, cold air descends Hot air at the equator rises and travels north / and south, precipitating rain as it ascends The dry air comes down at about 2SO north or south latitude (called the Horse latitudes) This is, not coincidentally, whe re most of the world 's deserts tend to be a This cycle described above is known as a Hadley cell, and this particular cell is the equatorial Hadley cell b Thc winds in the Hadley cells just north and south of the eq uator tend to blow to the east c These winds were named the trade winds, and facilitated much of the New World exploration by European explorers The region around the equator where the hot air rises is known as the do/drums a Sailboats have difficulty moving anywhere in the doldrums, hence the phrase "in the doldrums." Cold air at the poles descends, trave ls toward the equator and heats up Then, it rises near the Arctic and Antarctic circles a As it rises, it releases rain This is the polar Hadley cell b.ln between these regions, air circulates oppositely in a semi-stable system called the wastrels c The wastrels often give airplanes traveling from the U.S to Europe very strong tail winds, some­ times as hi gh as 200 mph EQuat o• • • Thermocline B EI Nino I EI Nino was named "the Son," in Spanish, by the Peruvians, because the patterns reflected that "he" would usually come around Christmastime EI Nino is a major change in the surface tempera­ ture of part of the Pacific Ocean, and a large region of warm surface water off the coast of Peru a The usual situation can be described thusly: Cold air from the Arctic and Antarctic converges at the equator off the coast of Peru, and heads westward b II heads toward Indonesia, where a semi-penna­ nent, low-pressure system exists c When a high-pressure system develop s over Indonesia, the wind stops blowing from the east to the west, and warm water begins to accumulate off the coast of Peru (it is no longer being cooled by the steady flow of cold air) A change in the temperature of the land or water beneath a body of air will change the way the body of air behaves a Hot air rises and carri es water; cold air sinks and is depleted of water b.Therefore, a major chan ge in the surface tem­ perature of a large part of the ocean will have a major effect on global weather patterns The meteorological effects of EI Nino are very complex, but they all begin with thi s region of warm water off the coast of Peru e La Nina I A large region of cold surface water off the coast of Peru is referred to as La Nina , La Nina, "the daughter," is so named for th~ opposite effects, in comparison to EI Nino's D Weather Patterns and Air Masses I The air masses that influence U.S weather fall into roug hly eight different categories They are classified according to thei r source region, and the nature of their source location (l and or ocean) a Continental Polar I Cold and dry air from the interior of Canada and Alaska ii It produces cold waves in the winter and heavy snows in the Great Lakes region b Continental Arctic i Very cold and dry air from the Arctic basin and Green land ice cap II It also produces cold waves in winter c Maritime Polar (Pacific) I Mild and cool air from the Northern Pacific Ocean ii It produces heavy orographic precipitation in the Wash ington State area, low clouds in the summer, nd low stratus clouds and fog in the winter a d Maritime Tropic i Warm, humid air from the Gulf of Mexico ii Brings hot and humid conditions, and frequent thunderstorms e Maritime Polar (Atlantic) i Cold, humid air from the Northwestern Atlantic ii Brings periods of cool, clear weather in summer and an occasional severe storm in winter f Maritime Equatorial I Warm, humid air from the subtropical Pacific Ocean II In the winter, it brings fog and drizzle to the south­ western U.S g Continental Tropical I Hot and dry air from the southwestern U.S and northern Mexico ii It bri ngs very desiccated conditions to the Great Plains and occasional droughts h Cyclones and Anti-Cyclones i Temperature variations cause pressure differences in the air ii These pressure differences cause the wind Around an area of low p ressure, the wind tends to move in a characteri stic counter-clockwise motion (clockwise in Southern Hemi sphere) called cyclonic flow The low-pressure area itself is called a cyclone Around an area of high pressure, the winds have a characteristic clockwise motion (count­ er-clockwise in Southern Hemisphere), called anti-cyclonic flow The area of high pressure is called an anti-cyclone A Thunderstorm Thunderstorms are cau sed by warm, moi st air rising though the atmosphere a As the air rises, it cools adiabatically (adiabatic cooling results from the gas ex panding) b.lf the ri sing air remains warmer than the sur­ ro unding air, it will continue to rise, as hot air is lighter than cold air c When it reaches sufficient altitude, it cools below its dew point and rain results The top of the thundercloud can be as high as 50,000 feet a The anvil-shaped top is the result of the higher parts of the cloud entering the j et stream A thunderstorm producin g one inc h of in on a sq uare yard of surface (3 feet by feet) will deposit about 2.5 million raindrops Beaufort Force Name 10 11 12 Calm Light Air Light Breeze Gentle Breeze Moderate Breeze Fresh Breeze Strong Breeze Moderate Gale Fresh Gale Strong Gale Whole Gale Storm Hurricane Miles Per Hour 73 B Downbursts and Mlcrobursts I Inside of a thunderstorm , there are very strong winds These winds resu lt from temperature and pres­ sure differences w ith in the c lou d a Winds going up are call ed updrafts, and are caused by hot air being li fted by a cold fron t b The downward winds are called downdrafts I The rain, which causes them falls, cooling the air and therefore, making it heavier ii A very intense downdraft is ca ll ed a downbursl and can generate winds of 70+ mph III Very small downbursts are called microbursts Downbursts and microbursts are lead ing causes of aircraft accidents e Tornadoes I A to rnado is a whirling vo rtex of wind Strictly defined, a/ilflllt'l is the co lumn of wind that descends from the cloud but does not yet touch the Earth The tornado begins when the nannel c loud makes contact Th e specif ic ca uses of tornadoes are currently unknown, but the large-scale impetus for these storm s is known a The effect is simil ar to an icc skater spinning very fast b When her arms are stretched out fully, she spi ns at a certain rate C As she brings her ann in , she spins faster and faster The effect is ca lled conservation a/angular momentum 5 A large cumulonimbus cloud has a slow, diver­ gent spin a As the warm air rushes upward through the cloud, it translates its slow rotation into the extremely fast rotation of the tornado 111 G.Ozone loss of life, especially on the right side of hurri· canes (in the North ern Hemisphere) The right side is especially dangerous because the wind has the speed of the storm and the speed of the wind relative to the center of the storm added together The ozone layer screens Ollt harmful ultraviolet rays from the sun Man-made chemicals called chlorojlourocar­ bons tend to both destroy the ozone layer and warm the surface of the Earth Chlorofiourocarbons (CFCs) are used in refrig­ eration, aerosols and insulation The result of the large quantities of manmade chemicals in the upper atmosphere has altered the chemistry of the ozone form ation process, and created holes in the ozone laye r over the Pol ar Regions The following is a compendium of facts about tornadoes: I More tornadoes occur in tornado alley (Texas, Missouri, Kansas, Oklahoma and Ohio) than any place on Earth They occur most frequently in May The strongest wind in a tornado can be as high as 300 mph A tornado in Bangladesh killed more than 1,000 people in 1989 The average path length ofa tornado is about miles long and 200 yards wide The largest tornado outbreak on record occurred on April 3, 1974, when 148 tornadoes struck j states and killed 315 people A waterspout is a tornado over water Most tornadoes spin counter-clockwise, the same direction as hurricanes FUJITA-PEARSON TORNADO SCALE Force Path Length Path (mph) (mUesY: - _W :: ;;.iclth 0-72 73-112 113-157 158-206 0-1 1-3.1 3.2-9.9 10-31 32-99 99-315 0-17 yd Light 18-55 yd Moderate 56-175 yd Considerable 176-556 yd 0.34-0.9 miles 1-3.1 miles D Hurricanes The initial step toward the formation of a hurri­ cane b egins with an agglomeration of thunder­ storms called a tropical wave a The tropical wave becomes a tropical depression when the thunderstorms organize themselves into a single system The next stage is the tropical storm, which is still more organized and has sustained winds 39 to 73 mph in range When the sustained winds reach the 74-mph m ark, the storm is said to be a hurricane a Hurricanes have a characteristic spi ral shape b The heaviest squalls are found near the center, which is a relatively calm region called the eye c The storm may be several hundred mil es across In the Northern Hemisphere, a hurricane spins counter-clockwi se In the Southern Hemisphere, a hurricane spins clockwi se In the Pacific, hurricanes are known as typhoons On average, there are about 6-10 hurricanes every year The most damaging part of a hurricane is the storm surge a The storm surge is an upswelling of water that accompanies the hurricane b The hurricane has a very low barometric pressure, and it literally sucks the water up into a bulge I The strong winds also whip the waves on top of the tidal bulge up to heights of 25 feet above normal sea level ii These tidal surges cause a great deal of damage and Scale Number Winds Storm Surge (m h) (feet) 74-95 96-110 111-130 130-155 >155 4-5 5-8 8-12 12-18 >18 Damage Minimal Moderate Extensive Extreme Catastrophic E Lightning I Excess elec­ trons in certain parts of cumu­ lonimbus clouds cause lightning a Within the cloud, air is swirling very fast b Smaller a nd larger drops of water hold onto their respective electrons with different am­ ounts of force , and so, drops of different sizes passing next to one another cause electrons to jump from one drop to another c The electrons congregate at the bottom of the cloud, giving it a negative electric charge d This negative charge causes the Earth beneath the cloud to gain a positive charge When the difference between the Earth and the cloud becomes great enough, a spark jumps across space, and lightn ing is produced a The flash heats the air in the immediate vicinity ofthe lightning bolt, which causes it to expand explosively b Thunder is caused by the pressure wave of this expanding, super-heated air The tempe rature of the air at the center of a lightning bolt can be as high as 55 ,000' F, which is almost six times hotter than the sur­ face of the sun A.Auroras I Auroras are glowing regions of the atmosphere caused by particles traveling along the Earth's magnetic field The particles, which reach the Earth via the solar wind, travel along the magnetic field lines of the Earth like beads on a wire When large quantities of these particles pass through the atmosphere at the same time, they cause it to glow B Mirages When air is very hot, like it is just above a roadway on a summer day, it can reflect light just like a mirror Often, it reflects the sky, making it appear as if water is on the ground C Rayleigh Scaner'." is the scattering of blue light by atoms in the atmosphere The other col­ ors are not affected, so when we look at the sky, we see only blue light being scattered toward us Rayleigh Scattering AIR F Air Pollution full spectrum I Sources a The major sources of air pollution are coal com­ bustion, agricultural by-products, manufacturing waste, and the combustion of oil b The direct introduction of pollutants into the atmosphere is called primary pollution c Pollutants that react chemically with other con­ stituents of the atmosphere to form harmful com­ pounds are called secondary pollutants Impact on Nature a Massive quantities of sulftlr dioxide and nitrogen oxides are emitted into the atmosphere every year by industri al processes and automobiles b Once there, they are transformed into weak nitric and sulfuric acids by very complex processes c The acidity of acid rain is about 4.5, midway between concentrated sulfuric acid and distilled water all colors produce white light blue light scattered by air *()ictures Appear Courtesy of Nlt1iorH11 Cent" Fe r Atmosp her ic K esca :-::hfUnl ~·:.'rsit ) Corpo tion For At r!!n5p ~ ~ ric R"::s!:afc h/Na lio!ll!! Science f oundiiliu!1 ""pic!urc£ Appear Courtesy (NOAA) l}hot(J Library (j or 'fhc N iU I(t IHI I O CC3!!I\: '\.!!(I Alr!losphcr!c Ad istration All nj,\hl_~ re'l