Lesson 402 - Hurricanes

Front 1

State the areas associated with tropical and extra tropical latitudes

Back 1

- tropical is atmosphere on equatorial side of subtropical highs
- extra tropical is areas not classified as tropical

402.1.1

Front 2

Chart the differences between tropical (TR) and extra tropical (ET) weather based on the following factors that control their evolution

Back 2

Thermal advection:
- insignificant (TR); very important (ET)
Fronts:
- none (TR); present (ET)
Surface convergence:
- very important (TR); important (ET)
Upper level flow:
- easterly (TR); westerly (ET)
General circulation:
- weak (TR); stronger (ET)
Motion:
- east to west (TR); west to east (ET)

402.2.1

Front 3

Indicate the start and finish dates of the hurricane seasons in North America

Back 3

- Atlantic: June 1st to November 30th
- Pacific: May 15th to November 30th

402.2.2

Front 4

Describe the 2 energy sources at work during the formation of hurricanes

Back 4

Sensible heat:
- warm ocean transfers heat to air just above it
Latent heat:
- released by enormous amount of water vapor condensing

402.3.1

Front 5

List the 6 elements required for the formation of a hurricane

Back 5

- latitude
- over ocean
- positive low level vorticity
- conditional instability
- mid tropospheric humidity
- minimum vertical shear

402.4.1

Front 6

Describe latitude as an element required for the formation of a hurricane

Back 6

- Coriolis effect required to induce and sustain cyclonic circulation
- forms within 5-15 degrees of equator

402.4.2

Front 7

Describe over ocean as an element required for the formation of a hurricane

Back 7

- sea surface temp threshold of 26.5 C
- hurricanes consume large amounts of ocean sensible heat energy

402.4.2

Front 8

Describe positive low level vorticity as an element required for the formation of a hurricane

Back 8

- form only in regions of positive low level vorticity
- larger the area, greater the potential
- intense convection generates convergent low level wind field
- this convergence produces increase of relative vorticity

402.4.2

Front 9

Describe conditional instability as an element required for the formation of a hurricane

Back 9

- can keep gaining energy until something causes it to rise and release all accumulated energy at once
- promotes deep convection

402.4.2

Front 10

Describe mid tropospheric humidity as an element required for the formation of a hurricane

Back 10

- form only where averaged values of mid level humidity are high
- dry mid levels erode convective clouds and lessen latent heat release
- assists in convective buildup

402.4.2

Front 11

Describe minimum vertical shear as an element required for the formation of a hurricane

Back 11

- prevents energy from being dispersed
- allows enhancement of convection currents
- high shear separates low and upper level features of a storm and system is torn apart

402.4.2

Front 12

List the meteorological hazards associated with hurricanes

Back 12

- wind
- rain
- thunderstorms
- tornadoes
- storm surge

402.5.1