Lecture 8 - Hurricanes

Question 1

Which way do winds in a cyclone blow in the northern and southern hemispheres?

Answer 1

North = counterclockwise
South = clockwise

Question 2

Tropical Cyclone?

Answer 2

Form over warm tropical or subtropical oceans

Question 3

Extratropical Cyclone?

Answer 3

Develop over land or water in temperate regions (farther north)

Question 4

What is the only difference between hurricanes/cylones/typhoons/nor’easters?

Answer 4

Their location

Question 5

Hurricane?

Answer 5

Tropical cyclones in Atlantic and Eastern Pacific oceans

Question 6

Typhoon?

Answer 6

Tropical cyclones in western Pacific Ocean and North of equator

Question 7

Cyclone?

Answer 7

Tropical cyclones in the Indian Ocean and Pacific Ocean south of the equator

Question 8

Nor’easter?

Answer 8

Extratropical cyclone moving northward along the east coast of NA

Question 9

EXAM Q: what is the wind speed of a category 4 hurricane on the Saffir-Simpson scale?

Answer 9

210-249km/h

Question 10

Who names the hurricanes?

Answer 10

The world meteoroloigcal organization names winds greater than 63 km/h from an alphabetical list of men and women’s names

Question 11

Tropical disturbance?

Answer 11

An organized area of thunderstroms peristing for more than 24 hours
- associated with an elongated area of low pressure

Question 12

Tropical depression?

Answer 12

A tropical disturbance with an increase in winds and faster spinning

Question 13

Tropical storm?

Answer 13

Has winds of at lest 62km/h, gets a name.

Not as strong as a hurricane

Question 14

Hurricane?

Answer 14

Winds of at least 119km/h

Question 15

What are the necessary conditions for hurricane formation?

Answer 15

Warm water at least 26 degrees to a depth several tens of meters
Atmosphere cools quickly upward from the surface
Little vertical wind shear

Question 16

Rain bands?

Answer 16

Areas of clouds and rain that spiral around a hurricane

- thunderstorms and surface winds increase in intensity toward the centre of the storm

Question 17

Eyewall?

Answer 17

Innermost band of clouds and rain, most intense weatehr

Question 18

Eye?

Answer 18

A circular area of calm conditions and broken clouds in the centre, most are smaller at the surface and widen upward

Question 19

Upward rotation _____

Answer 19

• draws air from the eye, causing dry air to sink into the centre
• causes air to flow out the top of sthe storm, which is critical for survival of the hurricane (allows additional warm, moist air to converge inward at the lower level of the storm)

Question 20

What controls hurricane movement?

Answer 20

• the coriolis effect

- steering winds

Question 21

Which way do hurricanes track in the Northern Hemisphere?

Answer 21

Hurricanes track westward and then curve to the right

- Hurricane tracks are influenced by the size and location of the bermuda high in the north atlantic

Question 22

How fast will a mature hurricane move?

Answer 22

19-27km/h

Question 23

What are the necessary conditions for the formation of an extratropical cyclone?

Answer 23

• Strong temperature gradient in the air

- Strong winds in the upper troposphere (ex. jet stream)

Question 24

What two jet streams exist in the Northern Hemisphere?

Answer 24

• Polar jet stream

- Subtropical jet stream

Question 25

How does the polar jet stream shift?

Answer 25

From the northern US in the winter to southern canada in the summer

Question 26

What causes jet streams to bend?

Answer 26

Large high-pressure ridges and low pressure troughs

Question 27

What is often produced when a bend in the jet stream turns south?

Answer 27

Pineapple express - origin near hawaii, brings warm moist air out of the tropics

Question 28

Nor’easters can form where?

Answer 28

In the merging of pola and subtropical jet streams off the southeast coast of the US

Question 29

How do extratropical cyclones develop?

Answer 29

• Start: low pressure centre along a frontal boundary
• Cold front on the Southwest, Warm front on the Northeast
• Cold air circles counterclockwise, and rises on the southeast corner
• Cold front merges with warm front to produce an occluded front
• Warm air is trapped aloft

Question 30

What kind of winds usually steer extratropical cyclones?

Answer 30

Winds in the middle of the troposphere

Question 31

Which regions are at risk for hurricanes?

Answer 31

Atlantic coast of Canada/US, gulf coast of US

Question 32

What is the atlantic hurricane season?

Answer 32

June 1st to November 30

Question 33

Storm Surge?

Answer 33

Rapid local rise in water level that happens when hurricane winds push waster into a shoreline

Question 34

What part of the hurricane produces the greatest storm surge and wind damage

Answer 34

Forward right quandrant

Question 35

What two mechanisms cause a storm surge?

Answer 35

• larger the area over which the wind blows (fetch)

- the lower the atmospheric pressure

Question 36

Overwash?

Answer 36

Sand eroded from the beach and deposited landward due to a storm surge

Question 37

What happens to winds once they make landfall?

Answer 37

Tend to decrease speed

Question 38

Rainfall from cyclones can cause _____

Answer 38

Inland flooding

Question 39

How does climate change affect cyclones?

Answer 39

Sea levels rising increases their severity

Question 40

What are some natural service functions of cyclones?

Answer 40

• Source of precipitation
• Equalize temperature of planet
• Benefit ecosystems; stir up nutrient rich waters, remove diseased trees, break apart corals

Question 41

What are some methods of tracking/predicting hurricanes?

Answer 41

• Weather satellites
• Aircrafts flown into the storm
• Dopplar radar
• Weather buoys

Question 42

EXAM Q: How many deaths resulted from the catagory 4 hurricane that hit Louisiana in 1866?

Answer 42

~400