Storms 5 (flooding, winds, waves, storm surge)

Saffir-Simpson Scale

measures hurricanes

• tropical depression, tropical storm, category 1-5

tropical cyclones

hurricanes and typhoons

Which way do cyclones spin in northern hemisphere?

• counterclockwise

• spiraling in

what are 3 characteristics of the center of the hurricane?

• relatively clear, calm, low pressure at sea level

hurricane are thunderstorms made of..

EYE WALL- ring of thunderstorms around the eye

SPIRAL BANDS- bands of thunderstorms extending out from the eye wall

Where is precipitation the heaviest in a cyclone?

in the eye wall

individual thunderstorms

• use warm humid boundary air as fuel

• use nearby supplies of fuel

• run out of fuel and die

• short lived (15-30min)

Supercells can last for hours

longer lasting thunderstorms

ambient atmosphere that has the right amount of

• wind shear that

  • continually blows fresh fuel into storm

  • or blows t storm to new regions (boundary layer fuel)

Hurricanes and their T storms can last for weeks because..

They manipulate environment to continually create new fuel of warm humid air from heat stored in the ocean

How do hurricanes create their own fuel?

• low pressure eye sucks in boundary-layer air

• as air gets closer to eye it moves faster

• waster winds create larger ocean waves

• evaporation from ocean surface enhanced with spray from waves

• adds moisture to boundary-layer air. when this air reaches base of eye wall

  • its warm

  • exceptionally humid (near 100% relative humidity)

  • contains tremendous amounts of sensible and latent heat

What ocean temperature is required for hurricane? what depth is required?

1) ocean surface temp mush be greater than 26 degrees celcius!

2) warm surface waters must be greater thab 60 meters deep!

How do hurricanes influence sea surface temperatures?

They cause sea surface temperature to cool due to wave induced turbulence in the upper ocean

• because of this water have to be greater than 60m to avoid having the hurricane kill itself

When is hurricane season in northern hemisphere?

September!! late summer, early fall

Where do hurricanes form

in tropics, but NOT equator

-why? Coriolis effect!! no spin at the equator

Hurricanes can only persist if:

• central pressure in eye remains low

  • to create wind, waves, fuck in fuel of humid warm air

• the hurricane remains over warm ocean

Hurricane weaken and die if:

• cannot generate sufficient fuel of warm humid air

  • happens if hurricane moves over cold water or land

• larger-scale weather systems interfere

Westerlies and, Trade winds, Bermuda hight

• hurricanes are steered by circulation in these areas. trade winds are closer to equator than westerlies

why can hurricanes last for weeks in spite of all their air molecules continually being blown into the core?

heavy condensation and precipitation from thunderstorms in the eye wall cause the hurricane core (eye+ eye wall to become very warm relative to its surroundings