Weather Systems. Energy in the Atmosphere The sun is the major source of energy for Earth Stars,...
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Transcript of Weather Systems. Energy in the Atmosphere The sun is the major source of energy for Earth Stars,...
Weather SystemsWeather Systems
Energy in the AtmosphereEnergy in the Atmosphere The sun is the major source of energy for EarthThe sun is the major source of energy for Earth Stars, including our sun, give off electromagnetic Stars, including our sun, give off electromagnetic
energy over the wide range of wavelengths that energy over the wide range of wavelengths that make up the make up the electromagnetic spectrumelectromagnetic spectrum Earth’s atmosphere filters out most of the short-wave Earth’s atmosphere filters out most of the short-wave
radiationradiation Most of the output from the sun that reaches the surface Most of the output from the sun that reaches the surface
of Earth is in the narrow band that we perceive as visible of Earth is in the narrow band that we perceive as visible lightlight
Earth also radiates electromagnetic energy, mostly Earth also radiates electromagnetic energy, mostly in the infrared (heat) part of the spectrumin the infrared (heat) part of the spectrum
Electromagnetic SpectrumElectromagnetic Spectrum
EvaporationEvaporation
Of the solar radiation that Of the solar radiation that reaches Earth, about ¾ reaches Earth, about ¾ evaporates water from the evaporates water from the oceansoceans Evaporation is the change of state from Evaporation is the change of state from liquidliquid to to
gasgas or or vaporvapor• Evaporation adds energy and matter to the Evaporation adds energy and matter to the
atmosphereatmosphere• DecreasesDecreases when water is covered or cooled when water is covered or cooled• IncreasesIncreases when water is uncovered, heated, and when when water is uncovered, heated, and when
wind blows over itwind blows over it
Three Stages of WaterThree Stages of Water Ice, liquid water, water vaporIce, liquid water, water vapor Energy that is absorbed or released during a Energy that is absorbed or released during a
change in state is called latent (hidden) heat, change in state is called latent (hidden) heat, a form of potential energya form of potential energy It is latent energy It is latent energy
because it does because it does not cause a change not cause a change in temperaturein temperature
Heat of FusionHeat of Fusion When the temperature of the ice reaches When the temperature of the ice reaches
0°C, it begins to melt0°C, it begins to melt As the ice changes to liquid, it absorbs 80 As the ice changes to liquid, it absorbs 80
calories per gramcalories per gram The The heat of fusionheat of fusion (the energy needed to melt (the energy needed to melt
one gram of one gram of ice is ice is 80 cal/g80 cal/g))
The temperature of The temperature of the ice does not the ice does not change until all the change until all the ice has meltedice has melted
Heat of VaporizationHeat of Vaporization When the temperature of the liquid water reaches When the temperature of the liquid water reaches
100°C, the boiling point of water, liquid water 100°C, the boiling point of water, liquid water changes to water vaporchanges to water vapor
The energy necessary to change one gram of a The energy necessary to change one gram of a substance from the liquid to the vapor state is substance from the liquid to the vapor state is called the called the heat of vaporizationheat of vaporization The heat of vaporization The heat of vaporization
of water is of water is 540 cal/g540 cal/g The gram of water absorbs The gram of water absorbs
540 calories of latent heat 540 calories of latent heat as it changes to vaporas it changes to vapor
After all the liquid water After all the liquid water becomes vapor, the becomes vapor, the temperature begins to temperature begins to rise againrise again
Latent Heat EnergyLatent Heat Energy The specific heat of water vapor is 0.5 cal/g·°CThe specific heat of water vapor is 0.5 cal/g·°C If the water vapor is cooled to 100°C, it will If the water vapor is cooled to 100°C, it will
condense and release the 540 calories of condense and release the 540 calories of latent heat it absorbedlatent heat it absorbed
As the cooling continues, the water will release As the cooling continues, the water will release the heat it absorbed the heat it absorbed while it was heatedwhile it was heated
It also releases the 80 It also releases the 80 calories per gram that calories per gram that was needed to melt was needed to melt the original icethe original ice
Synoptic Weather MapsSynoptic Weather Maps A weather map that shows a variety of A weather map that shows a variety of
atmospheric field quantitiesatmospheric field quantities May show information about temperature, air May show information about temperature, air
pressure, precipitation, and other weather pressure, precipitation, and other weather conditions at a conditions at a particular time and particular time and over a large over a large geographic areageographic area
Weather Station SymbolsWeather Station Symbols
Weather Station SymbolsWeather Station Symbols
Air MassesAir Masses The leading edges of air massesThe leading edges of air masses When a front passes, precipitation often When a front passes, precipitation often
accompanies the changes in temperature, accompanies the changes in temperature, humidity, and atmospheric pressurehumidity, and atmospheric pressure
The character of an The character of an air mass depends on air mass depends on its geographic originits geographic origin
Weather FrontsWeather Fronts
Fronts are shown by lines that separate Fronts are shown by lines that separate two air massestwo air masses
Symbols along the fronts indicate the Symbols along the fronts indicate the direction the fronts are moving and what direction the fronts are moving and what kind of front they arekind of front they are
StationaryStationary fronts are boundaries between fronts are boundaries between air masses that are not movingair masses that are not moving
OccludedOccluded fronts result from warm air being fronts result from warm air being pushed above the surface of Earth by pushed above the surface of Earth by cooler air closing in from both sidescooler air closing in from both sides
Front SymbolsFront Symbols
Natural HazardsNatural Hazards ThunderstormsThunderstorms
Most occur in the summer when the air is warm Most occur in the summer when the air is warm and moistand moist
Advancing cold fronts may push the warm air Advancing cold fronts may push the warm air upward, causing the formation of giant cumulus upward, causing the formation of giant cumulus clouds, and heavy precipitationclouds, and heavy precipitation
Lightning, damaging hail, and Lightning, damaging hail, and tornadoes are possibletornadoes are possible• Lightning strikes, flash floods Lightning strikes, flash floods
and tornadoes spawned by and tornadoes spawned by thunderstorms cause about thunderstorms cause about 100 fatalities per year in the US100 fatalities per year in the US
Natural HazardsNatural Hazards TornadoesTornadoes
Most common in the spring and early summer Most common in the spring and early summer over the central USover the central US
Are usually less than 0.3 miles (0.5 km) in Are usually less than 0.3 miles (0.5 km) in diameter and usually diameter and usually last for 10 min or lesslast for 10 min or less
Winds have been Winds have been measured by radar in measured by radar in excess of 300 mi/hr excess of 300 mi/hr
Natural HazardsNatural Hazards
HurricanesHurricanes Tropical depressions, areas of low pressure that Tropical depressions, areas of low pressure that
usually develop in the late summer and early usually develop in the late summer and early autumn in the Atlantic Ocean between South autumn in the Atlantic Ocean between South America and AfricaAmerica and Africa
When winds exceed When winds exceed 74 mi/hr the designation 74 mi/hr the designation is changed from tropical is changed from tropical storm to a hurricanestorm to a hurricane
Tropical Storm FormationTropical Storm Formation
Tropical Storm CategoriesTropical Storm Categories
CategoryWind Speed
(mph)Damage at
LandfallStorm Surge
(feet)
1 74-95 Minimal 4-5
2 96-110 Moderate 6-8
3 111-130 Extensive 9-12
4 131-155 Extreme 13-18
5 Over 155 Catastrophic 19+