28 terms

Tropical Storms and Hurricanes

Lecture 19
definition of a hurricane
an intense tropical cyclonic storm consisting of a warm-core low pressure ceel at its center, inward-spiraling rainbands, and having sustained winds in excess of 74 mph
name of hurricane in Atlantic Ocean and eastern Pacific Ocean
name of hurricane in western Pacific Ocean
name of hurricane in the Indian Ocean
characteristics of a hurricane
1. cyclonic storm with warm-core low pressure at its center
2. range in diameter from 100-600 mi.; average about 360 mi
3. form over warm ocean waters
4. strong pressure gradient to generate strong winds; strongest near the center, in the eye wall, and decreases outward
5. may have tornadoes within it; heavy rain, lightning, flooding, storm surge
6. have an average life span from 7-10 days, but may last over 2 weeks
requirements for formation
1. warm, moist air: yields greater instability and lift
2. ocean water temperatures >27 degrees Celsius (81 degrees Fahrenheit)
3. uplift initiated by an easterly wave (trade winds at the ITCZ)
4. must form between 5 degrees-20 degrees latitude for sufficient Coriolis Force to initiate rotation
tropical disturbance
the initial mass thunderstorms with weak, if any, cyclonic circulation
-usually originate in conjuction with an easterly wave
easterly wave
a large undulation or ripple in the normal trade wind pattern
tropical depression
stronger cyclonic circulation, greater development
-at this stage a number is given
tropical storm
well developed cyclonic circulation with the beginnings of an eye wall and rain bands, but usually no distinct eye yet
-at this stage the system is given a name
fully developed with strong cyclonic circulation, a distinct center, or "eye", eye wall and spiral rain bands
winds of a tropical depression
sustained winds near the center of the system between 25-37 mph
winds of a tropical storm
sustained winds between, in the eye wall, 38-74 mph
winds of a hurricane
sustained winds within the eye wall in excess of 74 mph
category 1 hurricane
category 2 hurricane
category 3 hurricane
category 4 hurricane
category 5 hurricane
>155 mph
center of low pressure, usually calm winds with weak downdrafts
eye wall
area of strongest pressure gradient and thus most intense winds
spiral bands
primarily stratus and nimbostratus clouds, with light to moderate rain
-largest part of the storm in terms of areal coverage
winds (destruction)
from strong, fast winds of the eye wall and also tornadoes within the system; even tropical storm strength winds can do damage
storm surge (destruction)
abnormal rise of sea level and high waves along the coast as a result of the strong winds and low pressure associated with the hurricane
-most severe on the right side of the storm as it makes landfall, because the winds here are blowing onshore and thus pushing even more water against the coastline
flooding (destruction)
due to heavy rains and the storm surge
-storm surge, flooding, and wind damage are usually more severe on the right side, especially the upper right quadrant, of the system
Atlantic Ocean (hurricane season)
June 1-November 30 (September is the peak month)
hurricane watch
that an approaching storm will make landfall within 24-36 hours
hurricane warning
that an approaching storm will make landfall in less than 24 hours