Geography 1111 Lecture 16 Notes
Geography 1111 Lecture 16 Notes GEOG 1111
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This 4 page Class Notes was uploaded by Bridget Notetaker on Wednesday September 21, 2016. The Class Notes belongs to GEOG 1111 at University of Georgia taught by Hopkins in Fall 2016. Since its upload, it has received 23 views. For similar materials see Intro to Physical Geography in Geography at University of Georgia.
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Date Created: 09/21/16
Geography 1111 Lecture 16 Notes Hurricanes, Typhoons, and Cyclones: o It is an intense tropical cyclonic storm consisting of a warm-core loq pressure cell at its center, inward- spiraling rain bands, and having sustained winds in excess of 119 kph (74 mph) o They are called by different names in different parts of the world: Hurricane: Atlantic Ocean and eastern Pacific Ocean Typhoon: western Pacific Ocean Cyclone: Indian Ocean Due to the necessary requirements for formation, they begin life only in warm, tropical waters, but may move to higher latitudes Characteristics: o It is a cyclonic storm with a warm-core low pressure at its center o They range in diameter from 100-600 miles (160 - 960 km) and average about 360 miles in diameter o A strong pressure gradient, generating strong winds, develops around the center, with the strongest winds in the eye wall o They are a large system of heavy rain, strong winds and lightning which may also have tornadoes within it Requirements for Formation: o These systems require warm, moist air which yields great instability and lift This is the systems fuel source o They must form over warm ocean waters with temperatures > 27°C (81°F) o The systems uplift is initiated by an easterly wave or area of disturbance, often associated with the trade winds along or near the ITCZ o The need for sufficient Coriolis Force to initiate rotation means they must form away from the Equator Hurricane Structure: o Eye: center of low pressure, usually with calm winds and weak downdrafts They average ~19 miles in diameter o Eye Wall: the area surrounding the systems eye and which exhibits the strongest pressure gradient and thus the most intense winds These winds are used to classify the systems to its stage and category The eye wall shows the greatest vertical cloud development, concentration of heavy rain and embedded tornadoes It is typically this section that causes the most damage o Spiral rain bands: typically the largest part of the storm in terms of areal coverage and consisting primarily of stratus and nimbostratus clouds, with light to moderate rain Often find thunderstorms imbedded within these bands Life Cycle of a Hurricane: o Tropical Disturbance is the term given to the initial, disorganized mass of thunderstorms showing a weak pressure gradient and little, if any, cyclonic circulation They sometimes originate in conjunction the ITCZ, but more often in association with or as an easterly wave, a large undulation or ripple in the normal trade wind pattern o Tropical Depression: occurs when the system shows stronger cyclonic circulation around a center, greater development of the cloud mass and has sustained winds near the center of the system between 25-39mph (40- 63kph) At this stage it is assigned a number o Tropical Storm is a system with well-developed cyclonic circulation around a strengthening low-pressure center, the beginnings of an eye wall and spiral rain bands, but usually no visibly distinct eye A tropical storm has sustained winds within the eye wall of between 38-73mph (63-118kph) and at this stage the system is given a name Hurricane: is a fully developed tropical system with strong cyclonic circulation, a visibly distinct center or “eye”, a strong eye wall and well organized spiral rainbands o The system has sustained winds within the wyw wall of 74mph (119kph) or greater o Different strengths of hurricanes can also be delineated: Category 1: 74-95 mph Category 2: 96-110 mph Category 3: 111-130 mph Category 4: 131-155 mph Category 5: >155 mph o Tropical systems have an average life span of 7-10 days, but may last over two weeks This covers from the first development of a Tropical Disturbance through to when a Hurricane finally dissipates Causes of Destruction from a Hurricane: o Winds: the strong, fast winds of the eye wall can cause great damage, as will any tornadoes which may develop within the eye wall or spiral bands Even tropical storm strength winds can do damage o Storm surge: the 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 The storm surge is 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 o Flooding: will occur due to the heavy rains and the storm surge The flooding rain amounts of a hurricane may be experienced hundreds of miles inland from the coast, while the storm surge is primarily only along the coast o Storm surge, flooding and wind damage are usually more severe on the right side, especially the upper-right quadrant, of the system Tropical Cyclone Seasons: o Tropical cyclone systems on average will occur during the times listed below for each area, but they have occurred outside these dates on occasion Atlantic Ocean: June 01 – November 30; ***peak month is September*** E. Pacific Ocean: June 01 – October 31 W. Pacific Ocean: June 01- December 31 (NH); January 01 – March 31 (SH) Indian Ocean: June 01 – November 30 (NH); January 01 – March 31 (SH) Hurricane Watch vs. Hurricane Warning: o A Hurricane Watch: indicates that hurricane force winds (>74mph) from an approaching storm will be felt within the watch area within 24-36 hours o A Hurricane Warning: indicates that hurricane force winds from an approaching storm will be felt within the watch area within 24 hours o Tropical Storm Watch and Warning have the same time periods, but are issued for those areas likely to be affected by the tropical storm force winds and not the hurricane force winds