Module 4: Severe Weather

Troposphere

90% of air molecules

Stratosphere

location of ozone layer

Thermosphere

Right above the mesosphere and in direct contact with high-energy radiation

Daily net radiation

balance between incoming shortwave and outgoing longwave radiation

Pressure gradient

generates wind from high to low pressure regions

Coriolis Force

arises due to Earth’s rotation

surface wind

_________ _________ is affected by pressure gradient, Coriolis force, and friction

Latent heat

• heat associated with some changing phase

  • absorbed energy when going from solid to liquid or liquid to gas 

  • releases energy when going from gas to liquid (condensation)

Air masses

Large volume of air that has roughly similar temperature and humidity 

Front

• transition zone between two different air masses (cold to warm or warm to cold)

  • More dense thing under less dense thing so warm air rises and cold air goes underneath

Warm front

temperatures rise when warm front passes 

• as air in a warm front over cooler air, it cools

• forms a gentle slope and a large area of atmospheric lifting

• Wide zone of clouds, precipitation before the warm front arises

Cold front

brings in colder air when it passes; often associated with violent weather 

• displaces the warm air upwards

  • warm air rises more quickly than at a warm front

  • the speed of the cold front advance is also much faster

Pressure

________ is higher at the Earth’s surface and decreases with altitude

nitrogen and oxygen

Constant gases in atmosphere mostly ________ and _________ with the first one being more

wind & water

Energy transport occurs via atmospheric _______ and _________ (ocean currents)

gravity, pressure gradient force, coriolis force, and friction

What creates and influences wind?

Pressure gradient force

generated by differences in pressure at same elevation

Friction

surface winds only

Isobar

each line represents a different pressure

high to low

Wind is created when air moves from ________ to ___________ pressure

North hemisphere

wind deflects right

South hemisphere

wind deflects left

warm; low

______ air rises at areas like the equator and creates _____ pressure region at the surface

cold; high

_______ air sinks at mid-latitudes and at the poles, creating _____ pressure region at the surface

Clouds

______ form due to water vapor in the atmosphere

Water

_______ absorbs or releases heat as it changes phases

Latent

________ heat is heat associated with changing phase

absorbed

Latent heat is _______ when ice melts and becomes liquid water or when liquid water becomes water vapor

absorb

Transitions that _________ heat is when water is in a high-energy phaes

Latent heat is _________ to the environment when vapor becomes liquid water through condensation or liquid water becomes ice

release

Transitions that _____ heat when water is at a low energy phase

Humidity

water vapor in the atmosphere

warmer

______ air can hold more water vapor

Relative humidity

how much vapor is in the air compared to the amount of vapor possible at that temperature

down; warms

Relative humidity goes __________ as air _________

Cloud condensation nuclei

tiny particles on which water can condense

Clouds

mixtures of water droplets and crystals

SW

Winds from ______ bring warmth

NW

Winds from ________ brings cold

air masses

Day to day weather patterns depend on the movement of large bodies of air called ____ _________

Air mass

huge volume of air with similar temperature and humidity

air masses

Movement of _____ _________ causes changes in temperature and humidity

Mid-latitude cyclones

• migrating low pressure weather system

• air spirals inward in N. Hemisphere

cyclogenesis, open stage, occluded stage, dissolution

4 stages of a midlatitude cyclone

cyclogenesis

first stage of formation of midlatitude cyclone

• Midlatitude cyclones (storms) develop at boundary between warm and cold air masses

• Stationary front develops at boundary between air masses

open stage

second stage of formation of midlatitude cyclone

• Cold air moves south (along cold front)

• Warm air moves north (along warm front)

• Gives counterclockwise winds around low pressure

occluded stage

third stage of formation of midlatitude cyclone

• Cold fronts move faster than warm fronts

• Eventually, it catches up with warm front

• Creates an occluded front

• Intense precipitation can be generated as all warm, humid air is lifted upwards

dissolution

final stage of formation of midlatitude cyclone

• dissipation

• no warm air remains at the surface

nor’easters

For ___________, to remain snowy in MA, storms needs to stay south and east of coastline