NS2 3.4 Fronts and Storms

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  1. CHAPTER 4 FRONTS AND STORMS 2. Mariners have much to fear when they are threatened by a severe storm. 3. A gale can strain rigging, spring seams, bend plates, smash…
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  • 1. CHAPTER 4 FRONTS AND STORMS
  • 2. Mariners have much to fear when they are threatened by a severe storm.
  • 3. A gale can strain rigging, spring seams, bend plates, smash equipment, and tear loose topside equipment.
  • 4. The prudent mariner will maneuver to stay clear of storms whenever possible.
  • 5. An experienced mariner should be able to see when weather disturbances are coming.
  • 6. Today’s radio communications provide regular weather summaries.
  • 7. The mariner at sea will carefully plot storm information relative to the vessel's position and proposed track.
  • 8. Fronts develop when air masses of different temperatures collide. Fronts are weather systems that are sometimes called waves, as in the term “cold wave.”
  • 9. Wave A body of air moving, resembling a wave of the sea; usually associated with hot or cold weather
  • 10. Cold Wave A rapid and considerable drop in temperature, usually affecting a large area
  • 11. Usually the colder of two air masses, being heavier, predominates and forces the warmer air upward.
  • 12. Predominate To be stronger or leading element or force
  • 13. A cold front displaces the warm air ahead of it upward.
  • 14. Cold Front The zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer
  • 15. A warm front moves upward over a retreating cold air mass.
  • 16. Warm Front A transition zone between a mass of warm air and the colder air it is replacing
  • 17. WARM FRONT COLD FRONT
  • 18. When a cold front overtakes a warm front it pushes the warm air up and converges with a cooler mass ahead of the warm front. Upper Air Cumulonimbus Flow Warm Air Cold Air Heavy Precipitation Cold Front
  • 19. Converge To come together
  • 20. Occluded Front The convergent frontal mass is called an occluded front.
  • 21. Occluded Front A composite front formed when a cold front overtakes a warm front and forces it aloft
  • 22. Frontal weather disturbances are normally 15 - 50 miles wide for a cold front and up to 300 miles wide for a warm front.
  • 23. The point where the cold and warm fronts converge is frequently the center of a low-pressure area.
  • 24. Fronts develop when air masses of different __________ collide. a. pressure b. size c. speed d. temperature
  • 25. Fronts develop when air masses of different __________ collide. a. pressure b. size c. speed d. temperature
  • 26. 90°N Polar Easterlies 60°N Arctic Frontal Zone 30°N Northeast Trade winds 0° Intertropical Convergence Zone Southeast Trade winds 30°S Antarctic Frontal Zone 60°S Polar Easterlies 90°S
  • 27. The convergence of 90°N the northeast trade Polar Easterlies winds of the 60°N Northern Arctic Frontal Zone 30°N Hemisphere and the Northeast Trade winds southeast Intertropical Convergence Zone 0° trade winds of Southeast Trade winds the Southern 30°S Hemisphere Antarctic Frontal Zone cause a band of 60°S unstable weather Polar Easterlies called the Intertropical 90°S Convergence Zone.
  • 28. Intertropical Convergence Zone (ITCZ) Situated or occurring between the tropic of Cancer and the tropic of Capricorn; band of unstable weather encircling the Earth
  • 29. The ITCZ is a storm development area that frequently breeds squalls.
  • 30. Squall A sudden, violent windstorm, often accompanied by intense rain, snow, or sleet
  • 31. 90°N Polar Easterlies 60°N The Arctic Frontal Zone develops Arctic Frontal Zone 30°N between the Northeast Trade winds arctic air of the 0° far north and Intertropical Convergence Zone the polar Southeast Trade winds maritime air of 30°S Antarctic Frontal Zone the North Atlantic 60°S and Pacific Oceans. Polar Easterlies 90°S
  • 32. Arctic Frontal Zone Located at or near the North Pole and pertaining to the division between dissimilar air masses
  • 33. The Polar Frontal Zone 90°N Polar Easterlies is formed by the 60°N Polar Frontal Zone convergence of the air that Arctic Frontal Zone 30°N flows toward Northeast Trade winds the equator 0° Intertropical Convergence Zone from the Polar Southeast Trade winds Easterlies and 30°S the Prevailing Antarctic Frontal Zone Westerlies (the Polar Frontal Zone 60°S temperate zones). Polar Easterlies 90°S
  • 34. Polar Frontal Zone A variable frontal zone of middle latitudes separating air masses of polar and tropical regions
  • 35. Temperate Moderate in respect to temperature; not subject to prolonged extremes of hot or cold weather
  • 36. The three primary frontal zones are the Intertropical Convergence Zone, the Arctic Frontal Zone, and the _________ Frontal Zone. a. Antarctic b. Occluded c. Polar d. Subtropical
  • 37. The three primary frontal zones are the Intertropical Convergence Zone, the Arctic Frontal Zone, and the _________ Frontal Zone. a. Antarctic b. Occluded c. Polar d. Subtropical
  • 38. You first notice a cold front when the sky darkens to the north and west. Soon thereafter, the ceiling lowers and rain begins.
  • 39. A rapidly moving cold front may move as much as 700 miles in one day.
  • 40. Passage of a cold front is usually marked by: • Wind shift • Drop in temperature • Rise in pressure • Rapid clearing
  • 41. Squall lines often precede a cold front. They are often violent, causing flash floods from downpours, cloudbursts, and extremely turbulent winds.
  • 42. What type of clouds often precede a cold front? a. Cirrus b. Cumulonimbus c. Nimbostratus d. Stratus
  • 43. What type of clouds often precede a cold front? a. Cirrus b. Cumulonimbus c. Nimbostratus d. Stratus
  • 44. Cirrus clouds in parallel precede a warm front, followed by cirrostratus, altostratus, nimbostratus, and finally stratus clouds.
  • 45. Visibility is poor in advance of a warm front. Frequently fog forms, and steady rain or drizzle prevails. Thunderstorms may develop ahead of a warm front.
  • 46. Passage of a warm front is usually marked by: • Wind shift • Rise in temperature • Pressure remains steady or gradually drops • Gradual clearing
  • 47. Warm fronts normally move less than 15 miles per hour. Cloud sequences may begin 48 hours in advance and occur 1,000 miles in advance of the front itself.
  • 48. A warm front will be preceded by what type of clouds? a. Cirrus b. Cumulus c. Nimbus d. Stratus
  • 49. A warm front will be preceded by what type of clouds? a. Cirrus b. Cumulus c. Nimbus d. Stratus
  • 50. An occluded front is an unstable frontal cyclonic rotation with a rapidly moving cold front.
  • 51. In a cold front type of occlusion, the cold front that remains on the surface is called the occluded front and the warm front that is raised aloft is called the upper front.
  • 52. Upper Front A warm front raised aloft by a cold front or a cold front raised aloft by a warm front
  • 53. Occlusions of this type: • Occur on eastern portions of continents • Have heavy frontal precipitation with thunderstorms • Are of less intensity than cold fronts
  • 54. Warm front occlusion Warm Air Cold front aloft Cold Front Warm Front (Fast-moving) (Slow-moving) Cool Air Cold Air In a warm front type of occlusion, the warm front that remains on the surface is called the occluded front and the cold front that is raised aloft is called the upper front.
  • 55. Occlusions of this type: • Occur chiefly in the Pacific Northwest • Cause severe icing and precipitation
  • 56. With occluded fronts, the front that is raised or lifted is called the ________ front. a. Dominate b. Occluded c. Shear d. Upper
  • 57. With occluded fronts, the front that is raised or lifted is called the ________ front. a. Dominate b. Occluded c. Shear d. Upper
  • 58. Thunderstorms occur within clouds with vertical development, such as cumulus and cumulonimbus. They are of short duration and difficult to forecast.
  • 59. Thunderstorm A transient storm of lightning and thunder, usually with rain and gusty winds, sometimes with hail or tornadoes
  • 60. The first stage of a thunderstorm is the cumulus stage characterized by an updraft of warm moist air into the atmosphere, clouds growing taller and taller.
  • 61. The second stage, called the mature stage of thunderstorm development, is characterized by both updrafts and downdrafts within the storm-producing cloud. Rain drops and hail form and begin to fall.
  • 62. The final stage is called the dissipating or anvil stage. The entire lower portion of the cloud becomes a downdraft and high winds flatten the top of the cloud. Rain falls heavily, but the storm dissipates in a short time.
  • 63. Dissipate To scatter in various directions; disperse; dispel
  • 64. Anvil A cloud with a flat top, shaped like an anvil
  • 65. There are many weather phenomena within thunderstorms. Rain is found in all thunderstorms. Hail and snow may also form and fall.
  • 66. Phenomena Something that is impressive or extraordinary
  • 67. A thunderstorm is most turbulent in the area of heaviest precipitation. Icing will often occur just above the freezing level, making this a very hazardous area for aircraft.
  • 68. Turbulent Being in a state of agitation or tumult; disturbed
  • 69. Thunderstorms usually occur with what types of clouds? a. Cirrus and Cirrostratus b. Cumulus and cumulonimbus c. Nimbus and Nimbostratus d. Stratus and Cirrostratus
  • 70. Thunderstorms usually occur with what types of clouds? a. Cirrus and Cirrostratus b. Cumulus and cumulonimbus c. Nimbus and Nimbostratus d. Stratus and Cirrostratus
  • 71. The leading gust of wind, sometimes called a microburst, is one of a thunderstorm’s dangers.
  • 72. Microburst An intense, localized downdraft of air that spreads on the ground, causing rapid changes in wind direction and speed, a localized downburst
  • 73. The speed of the first gust is usually the highest and can blow in any direction, even opposite of the wind pushing the storm. Such conditions can cause wind shear.
  • 74. Wind Shear A condition, dangerous to aircraft, in which the speed or direction of the wind changes abruptly
  • 75. Surging air currents in the thunderhead cloud create static electricity, the source of lightning.
  • 76. Lightning A brilliant electric spark discharge in the atmosphere, occurring within a thundercloud, between clouds, or between clouds and the ground
  • 77. The process is not completely understood. Positive charges develop near the top of the cloud, and negative particles accumulate in the lower reaches. An electrical discharge occurs when the strength of the charges overcomes the resistance.
  • 78. Lightning may flash within a cloud.
  • 79. Lightning may jump from cloud to cloud.
  • 80. Lightning may jump from cloud to ground or ground to cloud.
  • 81. Lightning occurs in two steps: • A leader of electrified (ionized) air runs between two oppositely charged regions • The second stroke is the one you see, and causes the thunder when the circuit is completed.
  • 82. Brush Fire Satellite Antenna Dish Lightning generates terrific heat, causing an explosive expansion of glowing hot air and producing the audible thunder. Burns
  • 83. Lightning follows the shortest route between a cloud and ground. High points are most likely to be struck. Do not stand under trees during a thunderstorm.
  • 84. Lightning also follows the easiest route to ground after striking.
  • 85. It is very unwise to be on or near bodies of water during a thunderstorm.
  • 86. Mountainous areas, especially with crevices or rushing mountain streams should be avoided during thunderstorms.
  • 87. Crevice A crack forming an opening; cleft; rift; fissure
  • 88. A fundamental rule for pilots is never to fly under or through a thunderstorm. But if unavoidable, it should be penetrated at 1/3 its height.
  • 89. A gust in a thunderstorm that blows in opposition to the surface wind can result in _________. a. a tornado b. an occluded front c. squalls d. wind shear
  • 90. A gust in a thunderstorm that blows in opposition to the surface wind can result in _________. a. a tornado b. an occluded front c. squalls d. wind shear
  • 91. The most intense and violent of localized storms is the tornado.
  • 92. Tornado A localized, violently destructive windstorm occurring over land, especially in the Middle West, and characterized by a long, funnel shaped cloud extending to the ground and made visible by condensation and debris
  • 93. Vortex Tornadoes are very small in diameter, usually 300 to 400 feet; but may continue on an erratic path for more than 100 miles. Winds in the vortex may exceed 300 mph.
  • 94. Vortex A whirling mass of air in the form of a visible column or spiral
  • 95. The speed of a tornado moving over the Earth may be 25 - 40 mph. The duration at any given spot may be only seconds, but the devastation can be almost total.
  • 96. A tornado forms as a funnel cloud on the forward edge of a fully developed cumulonimbus cloud. When the funnel touches the ground it is called a tornado.
  • 97. If a funnel forms over water, it is called a waterspout. It is laden with mist and spray.
  • 98. A dust devil is a small whirlwind, common in dry regions on hot, calm afternoons made visible by dust, debris, and sand it picks up from the ground.
  • 99. 1981 - 1990 F1 through F5 Tornados The Midwestern United States is the most tornado-ravaged area of the world.
  • 100. The extreme low pressure in the vortex of a tornado causes homes to explode outward from the normal pressure of air trapped inside.
  • 101. Where are tornadoes most common? a. Doldrums b. Equator c. Polar Frontal Zone d. Temperate zone
  • 102. Where are tornadoes most common? a. Doldrums b. Equator c. Polar Frontal Zone d. Temperate zone
  • 103. Tropical cyclones are subdivided into three categories: • Tropical depression – maximum wind less than 34 knots • Tropical storm – winds of 34 - 63 knots • Hurricane or typhoon – winds of 64 knots and up
  • 104. Cyclone A large scale atmospheric wind-and- pressure system characterized by low pressure at its center and by circular wind motion, counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere
  • 105. Large tropical cyclones occur in many places in the world and are called by various names.
  • 106. North Pacific Ocean North Atlantic Ocean Typhoon Baguios Hurricane Hurricane Cyclone Willy-willies Cyclone South Indian South Atlantic Ocean Ocean Pacific Ocean Hurricanes in the West Indies and on the International Date Line, Typhoons off China, Willy-willies off the west coast of Australia, and Baguios off the Philippines.
  • 107. Hurricane A violent, tropical, cyclonic storm of the western North Atlantic, having wind speeds of or in excess of 64 knots (74 mph)
  • 108. Typhoon A tropical cyclone or hurricane of the western Pacific area and the China seas
  • 109. Willy-willies A severe tropical typhoon off Australia
  • 110. Baguios A severe tropical typhoon off the Philippines
  • 111. ALBERTO BERYL CHRIS DEBBY ERNESTO FLORENCE GORDON. . . Today, hurricanes and typhoons are given alternating women's and men's names. Before 1978, all of these storms were named after women.
  • 112. The velocities of hurricanes are much less than tornadoes, but their destruction covers hundreds of miles and last much longer. It is the most destructive of all weather phenomena.
  • 113. Hurricanes and typhoons were named after women only until what year? a. 1964 b. 1974 c. 1978 d. 1988
  • 114. Hurricanes and typhoons were named after women only until what year? a. 1964 b. 1974 c. 1978 d. 1988
  • 115. The birth of a hurricane often occurs near the equator. They never occur right on the equator because the twisting Coriolis forces are not there.
  • 116. Hurricanes: • Vary in diameter from 60 - 1,000 miles • Have moderate winds on the outside and velocities as high as 175 kts (200 mph) toward the center
  • 117. At the center of a hurricane is the eye of the storm that averages 14 miles in diameter. This area is calm, with light winds and clear or moderately clear skies with some drizzle. Eye of The Storm
  • 118. Eye The approximate circular region of relatively light winds and fair weather found at the center of a hurricane
  • 119. The Atlantic hurricane starts as a tropical low, grows into a storm, and matures into a hurricane.
  • 120. When it curves to the northeast it comes over cooler waters and cooler air, reduces internal action and dissipates, eventually ending up as a gale or storm over the North Atlantic or North Sea.
  • 121. • Winds increase from the outer limits to the edge of the eye • Temperature rises and humidity falls at the center • Precipitation is heaviest in the right front quadrant
  • 122. Quadrant One quarter of a circle; an arc of 90 degrees
  • 123. Hurricanes are usually associated with great wind-caused tides called storm surges that inundate the land areas and cause more damage than the wind or rain.
  • 124. Inundate To flood; cover or overspread with water; deluge
  • 125. Hurricanes are born in what type of air mass? a. Cold and dry b. Cold and moist c. Hot and dry d. Hot and moist
  • 126. Hurricanes are born in what type of air mass? a. Cold and dry b. Cold and moist c. Hot and dry d. Hot and moist
  • 127. Hurricanes occur most frequently in September and October but can happen anytime from June to December. Heavy rains and tidal flooding are a danger.
  • 128. With less frequency, but often with greater violence, are hurricanes that originate in the Gulf of Mexico. They can wreak havoc throughout the Gulf Coast and Mississippi Valley.
  • 129. Tropical Cyclone Track
  • 130. When a typhoon veers into the Asian continent, it is usually accompanied by significant storm surge.
  • 131. Bay of Bengal Just as a hurricane may move into the Gulf of Mexico, a typhoon may sweep south of Indonesia into the Bay of Bengal and then the coast of southern Asia.
  • 132. In probably the greatest natural catastrophe of history, a typhoon swept over the Bay of Bengal in 1737. The storm pushed a 40-foot surge of water inland, killing 300,000.
  • 133. Catastrophe A sudden and widespread disaster
  • 134. A hurricane hit Galveston, Texas in 1900, killing 6,000.
  • 135. A hurricane hit New England in 1938, killing 600 and causing damage in excess of $250 million.
  • 136. The boardwalk at Atlantic City, New Jersey has been swept away several times.
  • 137. The city of Belize was totally destroyed by a hurricane in the late 1960s.
  • 138. One of the strongest hurricanes ever recorded in the Western Hemisphere was Hurricane Gilbert that hit the Yucatan Peninsula in 1988, killing 500 and rendering 500,000 homeless.
  • 139. One of Florida’s greatest disasters happened in 1992 when Hurricane Andrew crossed the Florida Peninsula.
  • 140. Hurricane Katrina caused major damage to the New Orleans area. Levies broke that caused major flooding of the city.
  • 141. Hurricane Katrina
  • 142. Devastation of Hurricane Katrina
  • 143. DANGEROUS SEMI-CIRCLE NAVIGABLE SEMI-CIRCLE Northern Hemisphere Southern Hemisphere Cyclonic winds rotate counterclo
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