The Atmosphere

WeatherMeteorology Study of atmospheric phenomena

Weather Current state of the atmosphere

Air DensityLike most substances, cold air is more dense than warm air

Cold air will sink, hot air will riseAir MassesLarge body of air that takes on characteristics of area it covers (land and water) Air Mass Modification

Wind SystemsJet Streams High altitude, westerly windsResponsible for most of our weather in our country

Pressure SystemsLow pressure air risesClouds and precipitation

High pressure air sinks and spreadsFair weather

Wind caused by movement of air molecules

Cool dense air sinks, forces warm, less dense air upwardAir Pressure and WindFrontsNarrow region separating two air massesCold cold air displaces warmWarm warm air displaces coldStationary do not displaceOccluded warm squeezed between cold

Water in AtmosphereHumidityAmount of water vapor in the air

Relative Humiditywater vapor in the air compared to how much water vapor the air is capable of holding

Warm air holds more moistureCloud FormationCondensation Nuclei small particles in atmosphere which water condenses aroundMillions = cloud

Coalescence droplets collide, become bigger

Precipitation droplets become too big and fall

Using Weather Models

Using Weather Models

Using Weather Models

Acid precipitation Acid rain, acid fog, acid snow

Reaction of pollutants like SO2 and NO with water, oxygen, and oxidants to form acids that fall to surface in precipitation:

sulfuric acid (H2SO4)

nitric acid (HNO3)

Acid precipitationAcid precipitation is created by reactions in the atmosphere, and can fall many miles from where pollution originated.Figure 11.18

Acid precipitationAcidity varies geographically. (Orange = more acidic) Industrialized areas and regions downwind of them suffer most.

Figure 11.20Acid precipitationAcid precipitation has killed these conifer trees in the mountains of North Carolina.From The Science behind the Stories

Acid precipitationThis can be seen in data from New Hampshires Hubbard Brook Experimental Forest, where acid rain was first studied. pH has increased (rain has become less acidic) since 1970, but is still much more acidic than normal rain.

From The Science behind the StoriesSeasonal WeatherWhy do we have different weather in different seasons?

Why do we even have the seasons? What is the cause?Weather?Climate?

Severe StormsThunderstormsGenerates lightning and thunderFrequently produce gusty winds, heavy rains, and hail45,000 a day across the world

DevelopmentWarm, humid air rises in unstable environment

Uplift carries warm, moist air into cooler part of atmosphere

DevelopmentPrecipitation will stay uplifted until heavier than uplift force

DevelopmentDowndrafts throughout the cloud (cold air)

Storm dies

TornadoesTake form of rotating column of air called vortexUplift turns vortex vertical

Tornado IntensityPressure inside lower than outsideAir rushes in to equalize pressureWinds may reach 480 km/h (300 mph)

HurricanesWhirling cyclones that produce winds of at least 119 km/hrU.S. - hurricanes

DevelopmentLate summer warm waters to provide heat and moistureEye wall center wall that surrounds center of stormHighest winds and heaviest rain fallWarm, moist air rushes upDevelopmentEye air is descending No precipitation or windHigh pressure

Hurricane IntensitySaffir-Simpson Hurricane Scale