Hurricanes

Question 1

Jetstream

Answer 1

• Narrow, fast air flow in the upper atmosphere, from west to east
• At mid latitudes, ~10 km high
• Can cause unusual weather by steering air masses

Question 2

Small-scale wind patterns

Answer 2

Sea breeze (daytime)
- land warms faster than the ocean
- air rises over the land, sucking in air

Offshore breeze (night)
- land cools faster than the ocean
- air moves back out to sea

Question 3

Fronts

Answer 3

Boundaries between two different air masses, where the colder air always moves underneath the warm air
- warm front - warm air mass moves to colder area
- cold front - cold air mass moves to warmer area

Question 4

Low vs high pressure systems

Question 5

Tropical storms

Answer 5

• hurricane
• round, no fronts
• warm water, latent heat
• formed in single air mass with a warm core

Question 6

Extratropical storms

Answer 6

• nor’easter
• comma shape, cold or warm front
• pressure differences “baroclinicity”
• formedw hen two air masses meet, has a cold core

Question 7

What are hurricanes?

Answer 7

• Large, swirling storms with strong winds and significant rainfall
• great masses of warm, humid, rotating air, bringing strong winds and torrential rain
• occur only in tropical oceans
• sustained winds > 120 km/hr (75 mph)

Question 8

How do hurricanes form?

Answer 8

• warm ocean, provides heat to evaporate water
• high to low pressure, picking up moisture from ocean, absorbing latent heat
• air rises, cools, condendes, releases latent heat

Question 9

Hurricanes as heat engines

Answer 9

Heat energy from the ocean driving mechanical work
- air moves higher to lower pressure
- heat goes from ocean to air via latent heat of evaporation
- air is approx isothermal, nbut wetter and greater volume

Question 10

Hurricane ingredients

Answer 10

1. warm sea surface temperature (> 26.5, > 80F) over large area, warm water supplies heat and humidity to overlying air
2. Instability in atmosphre (rising air mass), fueled by surface warming, whcih decreases air density
3. Little/no vertical wind shear through troposphere
4. Sufficient lattitude >5-10 degrees off equator such that coriolis kicks in

Question 11

What can slow a hurricane?

Answer 11

• Intense cyclonic winds generates upwelling in ocean
• If upwelling is strong enough, the colder water rises to the surface, starving the hurricane of energy

Question 12

Death of a hurricane

Answer 12

energy lost due to friction = dnesity of air * drag coefficient * wind speed^3

Question 13

Hurricane damage

Answer 13

• high winds
• intense rainfall
• storm surge

Question 14

Storm surge

Answer 14

• Usually the largest on the side of the hurrican where the winds push ocean water onto shore
• flooding is worse when storm surge combines with high tide