NS2 3.2 Clouds and Fog
- 1. CHAPTER 2 CLOUDS AND FOG
- 2. Tiny particles of dust, pollen from plants, factory smoke, and salt particles from oceans are always present in the air. These fragments are called hygroscopic nuclei.
- 3. Hygroscopic Nuclei Tiny particles that absorb or attract moisture from the air
- 4. Cloud A mass of hygroscopic nuclei that have soaked up moisture from the water vapor in the air.
- 5. Clouds form when: • Water vapor rises • Vapor condenses • Droplets cling to hydroscopic nuclei • Nuclei bunch together and form clouds or fog
- 6. Three things may happen to the water droplets: • Reevaporate and rise • Rise and freeze into ice crystals • Collide with other nuclei and form larger drops
- 7. Cloud formations give clues concerning the forces at work in our atmosphere.
- 8. Fragments of matter that are always in the air are called _________ nuclei. a. hydroscopic b. hygroscopic c. psychroscopic d. psychrodropic
- 9. Fragments of matter that are always in the air are called _________ nuclei. a. hydroscopic b. hygroscopic c. psychroscopic d. psychrodropic
- 10. Cirrus Stratus There are three basic cloud types. Cumulus
- 11. Cirrus A cloud of a class characterized by thin white filaments or narrow bands and a composition of ice crystals: of high altitude, about 20,000 - 40,000 feet
- 12. Cumulus A cloud of a class characterized by dense individual elements in the form of puffs, mounds, or towers, with flat bases and tops that often resemble cauliflower
- 13. Stratus A cloud of a class characterized by a gray, horizontal layer with a uniform base, found at a lower altitude than altostratus, usually below 8,000 feet
- 14. There are also other types of clouds having names with combinations of the following: • Nimbus - rain • Alto - high • Fracto - fragmented or windblown
- 15. Clouds are sometimes classified by altitudes at which they most frequently occur: • Low - surface - 7,000 feet • Middle - 7,000 - 20,000 feet • High - above 20,000 feet • Towering - exceptionally high cloud with its base in low-altitude
- 16. Middle clouds seldom attain heights greater than 13,000 feet in polar regions but may reach 23,000 - 45,000 feet in temperate and tropical zones.
- 17. There are ten general types of clouds grouped into low, middle, and high categories.
- 18. Low Clouds Stratus Nimbostratus Stratocumulus Cumulus Cumulonimbus
- 19. Stratus • Lowest cloud type • Gray layer with uniform base • May cause drizzle, but never rain • Fog becomes stratus when it lifts
- 20. Nimbostratus • Dark, shapeless, rain-laden • Often have streaks of rain extending to ground • Often seen in summer at base of thunderheads • Brings steady, heavy snow in winter
- 21. Nimbostratus A cloud of a class characterized by a formless layer that is almost uniformly dark gray, a rain cloud of the larger type, of low altitude, usually below 8,000 feet
- 22. Thunderhead The upper portion of a cumulus cloud characterized by dense, sharply defined cauliflower-like upper parts and sometimes of great verticality
- 23. Stratocumulus • Irregular, rounded masses spread out in puffy or rolling layers • Usually gray with darker spots • Do not produce rain • Usually precede bad weather
- 24. Stratocumulus A cloud of a class characterized by large dark, rounded masses, usually in groups, lines, or waves, the individual elements being larger than those in altocumulus and the whole being at a lower altitude, usually below 8,000 feet
- 25. Cumulus • Dense, puffy clouds with a beautiful, cauliflower-like appearance • They rise by day and disappear at night • Fleecy cumulus clouds usually mean fair weather ahead
- 26. Fleecy Consisting of, or resembling a fleece (soft, fluffy)
- 27. Cumulonimbus (Thunderheads) • Dense clouds of the towering variety • The base is a dark nimbus rain cloud • May produce severe thunderstorms and tornadoes
- 28. Cumulonimbus A cloud of a class indicative of thunderstorm conditions, characterized by large, dense towers that may reach altitudes of 75,000 feet, uniform except for the tops, which appear fibrous because of the presence of ice crystals
- 30. Altocumulus • Gray or whitish layers, puffy, fleecy • Made up of water droplets • Sometimes produce a pale blue or yellow corona • Presence means rain is probable within 24 hours
- 31. Altocumulus A cloud of a class characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus: of medium altitude, about 8,000 - 20,000 feet
- 32. Altostratus • Dense sheets of gray or blue • Sun or Moon will show through but without corona • Light rain is likely within 24 hours
- 33. Altostratus A cloud of a class characterized by a generally uniform gray sheet or layer, lighter in color than nimbostratus and darker than cirrostratus: of medium altitude, about 8,000 - 20,000 feet
- 34. High Clouds Cirrus Cirrostratus Cirrocumulus
- 35. Cirrus • Thin, wispy, made up of ice crystals • Called “mare’s tails” • If scattered, indicate clear, cold weather • If in parallel lines, indicate violent change in weather within 36 hours
- 36. Cirrostratus • May nearly cover the sky with a filmy cloud • Curly appearance at their edges • Form large halos around the Sun and Moon • Indicate clear and cold weather
- 37. Cirrostratus A cloud of a class characterized by a composition of ice crystals and often by the production of halo phenomena and appearing as a whitish and usually somewhat fibrous veil, often covering the whole sky and sometimes so thin as to be hardly discernible: of high altitude, 20,000 - 40,000 feet
- 38. Cirrocumulus • Thin, patchy clouds that sometimes form in wavelike patterns • Do not leave shadows • Precipitation usually follows within 24 hours
- 39. Cirrocumulus A cloud of a class characterized by thin, white patches, each of which is composed of very small granules or ripples: of high altitude, 20,000 - 40,000 feet
- 40. Thunderheads start at almost any altitude and sometimes extend to heights of as much as 75,000 feet. The name given to these clouds is __________. a. nimbostratus b. stratocumulus c. cumulus d. cumulonimbus
- 41. Thunderheads start at almost any altitude and sometimes extend to heights of as much as 75,000 feet. The name given to these clouds is __________. a. nimbostratus b. stratocumulus c. cumulus d. cumulonimbus
- 42. Clouds have been leading lost seamen, navigators, and explorers to land since the days of the earliest hardy sea voyagers.
- 43. Stationary clouds on the horizon usually indicate an island is close by.
- 44. In the tropics, clouds often reflect the colors of the sandy beaches or coral reefs below.
- 45. Precipitation (rain, snow, sleet, and hail) cannot occur without clouds.
- 46. Temperature and presence of hygroscopic nuclei or ice crystals determine if there will be precipitation and in what form it will take.
- 47. Raindrops form when moist air is cooled to the point where the moisture condenses into heavy drops.
- 48. Not to Scale Cloud moisture droplets are 1/2,500 of an inch in diameter. If the Large Raindrop droplet grows to 1/125 of an inch, it will fall from the cloud. The combining of moisture droplets is called coalescence. Small Raindrop
- 49. Coalescence To grow together into one body
- 50. Coalescence occurs in two known ways: • Bigger droplets move about slowly, bump into other droplets and combine with them (low clouds).
- 51. Coalescence occurs in two known ways: • Ice crystals and water droplets form near each other, the droplets evaporate and resulting vapor collides with ice crystals and condenses into snow or ice pellets. They melt into rain as they pass through warmer air at lower altitudes.
- 52. _________and the presence of hygroscopic nuclei will determine whether or not there will be precipitation and what form it will take. a. Humidity b. Temperature c. Altitude d. Pressure
- 53. _________and the presence of hygroscopic nuclei will determine whether or not there will be precipitation and what form it will take. a. Humidity b. Temperature c. Altitude d. Pressure
- 54. Rainmaking has been a concern of humans since the most ancient times.
- 55. Rain dances, sacrifices, drums, cannons, and smoke have all been used in an attempt to make rain, especially during a drought.
- 56. Drought A long period of dry weather that is injurious to crops, animals, and humans
- 57. Seeding a large cumulus cloud with one pound of artificial nuclei made of dry-ice or silver-iodide crystals can start a shower.
- 58. Seeding Sowing or scattering clouds with crystals or particles of silver iodide or solid carbon dioxide to induce precipitation
- 59. Silver-Iodide Crystals A pale yellow, water-insoluble solid, which darkens on exposure to light: used chiefly in medicine, photography, and artificial rain making
- 60. Seeding can cause: • Rain to fall sooner • More rain to fall • Rain to fall from a cloud that normally would not produce rain
- 61. Seeding cannot cause: • Rain to fall from fair skies or fair-weather cumulus clouds • Rain to fall over a large area
- 62. Sleet occurs when rain formed in relatively warm air falls through a layer of freezing air.
- 63. Sleet Precipitation in the form of ice pellets created by the freezing of rain as it falls
- 64. Hail usually occurs in the summertime. It begins as raindrops, that updrafts take to greater heights. They are coated with water from lower clouds, lifted again and again until too heavy to be lifted.
- 65. Hail Showery precipitation in the form of irregular pellets or balls of ice more than 1/5 inch in diameter
- 66. Most hailstones are smaller than marbles. Hailstones as large as baseballs have killed people and animals.
- 67. In wintertime, when the upper air is very cold, water vapor will condense into ice crystals. Snow is the result.
- 68. Dew is water vapor that condenses on objects that have cooled below the condensation point of the air around them.
- 69. Dew Moisture condensed from the atmosphere and deposited in the form of small drops upon any cool surface
- 70. Frost is similar to dew, but it forms at temperatures below freezing.
- 71. Frost A covering of minute ice needles, formed from the atmosphere at night upon the ground and other exposed objects when they have cooled by radiation below the dew point, and when the dew point is below the freezing point
- 72. Water vapor that has condensed on objects that have cooled below the freezing point is called ___________. a. sleet b. dew c. hail d. frost
- 73. Water vapor that has condensed on objects that have cooled below the freezing point is called ___________. a. sleet b. dew c. hail d. frost
- 74. Fog is really a low-lying cloud that is near or touching the surface of the Earth.
- 75. Fog A cloudlike mass or layer of minute water droplets or ice crystals near the surface of the Earth, appreciably reducing visibility
- 76. Fog formation requires the presence of moisture, a gentle breeze, and a combination of warm and cold temperatures.
- 77. Fog is hazardous to aviation because it limits both ceiling and visibility.
- 78. Ceiling The height above ground level of the lowest layer of clouds that cover more than one half the sky
- 79. Visibility The distance at which a given standard object can be seen and identified with the unaided eye
- 80. Fog at sea is a continual hazard to safe navigation.
- 81. Fog at Sea
- 82. The nautical "Rules of the Road" require that extra lookouts be stationed aboard ship in foggy conditions.
- 83. Rules of the Road Any of the regulations concerning the safe handling of vessels with respect to one another, imposed by a government on ships in its own waters or upon its own ships on the high seas
- 84. Fog at sea is frequently formed through a process known as advection. Fog is likely to develop when warm air that has passed over warm water moves to an area of colder water.
- 85. Advection The horizontal transport of atmospheric properties The horizontal flow of air, water, etc.
- 86. When warm moist air comes in contact with colder water, advection fog forms.
- 87. Advection fog is the name given to air-mass fog produced by air in motion, or to fog formed in one place and transported by wind to another. It will usually dissipate when the Sun rises.
- 88. Dissipate To scatter in various directions; disperse; dispel
- 89. Puget Sound Newport San Francisco New York Norfolk Los Angeles San Diego Every Sailor is aware of the fogs that blanket the harbors and coastlines near these areas.
- 90. Steam fog is a type of advection fog formed by air saturation.
- 91. Saturation A condition in the atmosphere corresponding to 100 percent relative humidity
- 92. In the far north, "sea smoke" can be seen in the late fall or winter when a river or pond "steams" as frigid air cools the water until it begins to form ice.
- 93. Sea Smoke Fog caused by cold air flowing over a body of comparatively warm water, the vapor condensing in small convective columns near the water surface and giving the appearance of smoke or steam
- 94. The heat that the Earth radiates causes radiation fog. It forms only at night, over a land surface. The Sun usually burns the fog away.
- 95. Radiation Fog Fog produced by the nocturnal cooling of the surface boundary layer to a temperature at which its content of water vapor condenses
- 96. The movement of cold air masses causes frontal fog. It is common in the upper Midwest.
- 97. Frontal Fog A fog caused by the movement of two dissimilar air masses
- 98. A type of fog formed by air saturation is called ______ fog. a. steam b. frontal c. radiation d. advection
- 99. A type of fog formed by air saturation is called ______ fog. a. steam b. frontal c. radiation d. advection
- 100. Q.1. What does the term hygroscopic nuclei mean?
- 101. Q.1. What does the term hygroscopic nuclei mean? A.1. Particles that readily absorb moisture
- 102. Q.2. What are examples of hygroscopic nuclei?
- 103. Q.2. What are examples of hygroscopic nuclei? A.2. Particles that are present in the air, such as dust, smoke, and pollen
- 104. Q.3. How are raindrops formed?
- 105. Q.3. How are raindrops formed? A.3. Raindrops are formed when moist air is cooled to the point where the moisture condenses into heavy drops.
- 106. Q.4. What are the three basic types of clouds?
- 107. Q.4. What are the three basic types of clouds? A.4. Cirrus, cumulus, and stratus
- 108. Q.5. What does the prefix “fracto” mean?
- 109. Q.5. What does the prefix “fracto” mean? A.5. Fragmented or wind-blown
- 110. Q.6. What clouds are made of water droplets, sometimes laid out in parallel bands?
- 111. Q.6. What clouds are made of water droplets, sometimes laid out in parallel bands? A.6. Altocumulus clouds
- 112. Q.7. What accounts for the different shapes and altitudes of clouds?
- 113. Q.7. What accounts for the different shapes and altitudes of clouds? A.7. Changes in the atmospheric conditions
- 114. Q.8. What clouds are often called “mares’ tails?”
- 115. Q.8. What clouds are often called “mares’ tails?” A.8. Cirrus clouds
- 116. Q.9. What altitudes are associated with high, middle, and low clouds?
- 117. Q.9. What altitudes are associated with high, middle, and low clouds? A.9. High: above 20,000 ft. Middle: 7,000 to 20,000 ft. Low: surface to 7,000 ft.
- 118. Q.10. How are clouds generally named?
- 119. Q.10. How are clouds generally named? A.10. According to their appearance and altitude
- 120. Q.11. What are the main types of low clouds?
- 121. Q.11. What are the main types of low clouds? A.11. Stratus, nimbostratus, and stratocumulus
- 122. Q.12. What are the main types of middle clouds?
- 123. Q.12. What are the main types of middle clouds? A.12. Altocumulus and altostratus
- 124. Q.13. What are the main types of high clouds?
- 125. Q.13. What are the main types of high clouds? A.13. Cirrus, cirrostratus, and cirrocumulus
- 126. Q.14. What type of weather is associated with cumulonimbus clouds?
- 127. Q.14. What type of weather is associated with cumulonimbus clouds? A.14. Thunderstorms and tornadoes
- 128. Q.15. What weather condition follows cirrocumulus clouds?
- 129. Q.15. What weather condition follows cirrocumulus clouds? A.15. Precipitation