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Chapter 4 - Title

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Chapter 4 - Title

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    1. Chapter 4 - Title

    2. Contents the Hydrologic Cycle water vapor in the atmosphere dew, frost, haze and fog cloud types

    3. The Hydrologic Cycle Water is critical for our survival on this planet Very important for creating weather Very important for transporting heat Is observed in all three phases in the atmosphere - the only substance that can do this

    4. Processes in the Hydrologic Cycle evaporation condensation precipitation run off transpiration

    5. Question Does more water evaporate into the hydrologic cycle from the oceans or from land? 85 % from oceans, 15 % from land.85 % from oceans, 15 % from land.

    6. The Hydrologic Cycle 85% of evaporation occurs over the oceans If all vapor in atmosphere were to condense and fall = 1 inch of rain Why is it impossible to dry out the atmosphere? It is impossible to dry out he atmosphere because the water in the system is in continual cycling. It would be replaced very quickly.It is impossible to dry out he atmosphere because the water in the system is in continual cycling. It would be replaced very quickly.

    7. Evaporation, Condensation, and Saturation Magnify surface, H2O molecules bouncing around. Molecules moving at different speeds. Some have enough speed to break away, liquid ? vapor [evaporation] http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/atmospheric_moisture/concept_of_saturation.htmhttp://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/atmospheric_moisture/concept_of_saturation.htm

    8. Question Would you expect water in a glass to evaporate more quickly on a windy, warm, dry summer day or on a calm, cold, dry winter day? Explain. Warming the glass and windy conditions will increase evaporation on the Summer day.Warming the glass and windy conditions will increase evaporation on the Summer day.

    9. Factors Affecting Evaporation Dust particles act as condensation nuclei (more on these later). (b) Wind and heat enhances evaporation. (c) Surface tension holds water molecules at the surface. (d) Evaporation increases. Dust particles act as condensation nuclei (more on these later). (b) Wind and heat enhances evaporation. (c) Surface tension holds water molecules at the surface. (d) Evaporation increases.

    10. Moisture Variables There are a number of ways one can specify the amount of moisture (referred to as humidity) in the air What are they? Absolute humidity specific humidity vapor pressure saturation vapor pressure relative humidity mixing ratio saturation mixing ratio wet-bulb temperature dew-point temperature For this course you only need to know the terms in red.For this course you only need to know the terms in red.

    11. Expressing the Amount of Water Vapor in the Atmosphere Ignore absolute humidity (m/v), specific humidity (m/m), and mixing ratio (Don’t ignore if want to be a Met major) Ignore absolute humidity (m/v) (but don’t ignore it when working on CW4!)Ignore absolute humidity (m/v) (but don’t ignore it when working on CW4!)

    12. Saturation Vapor Pressure When the air parcel is saturated… Vapor pressure (V.P.) = saturation vapor pressure (S.V.P.) S.V.P. = max possible pressure due to water vapor Depends only on T, not P since water vapor acts independently of the other constituents in air Air does NOT hold water vapor. Water vapor exists as a gas independent of other gases

    13. Why Air Does Not Hold W.V. Evaporation increases with temperature, not because the holding capacity of the air changes, but because the more energetic molecules can evaporate more readily. See: http://www.ems.psu.edu/~fraser/Bad/BadClouds.html http://www.shorstmeyer.com/wxfaqs/humidity/humidity.html http://www.ems.psu.edu/~fraser/Bad/BadClouds.htmlhttp://www.ems.psu.edu/~fraser/Bad/BadClouds.html

    14. S.V.P. – Dependence on T For each 10 ° C (18 ° F) increase, saturation pressure doubles Saturation level of the air is directly related to the air's temperature. As air temperature increases, more water can remain in a gas phase. To maintain equilibrium the number of water molecules above the surface increases. And so at higher temperatures, it takes more w.v. to saturate the air. More w.v molecules exert a higher pressure. As temperature decreases, water molecules slow down and there is a greater chance for them to condense onto surfaces. Note that below zero degrees Celsius the curve splits, one for the saturation point above a liquid surface (liquid-vapor) and one for a surface of ice (ice - vapor). The first thing you might be wondering is how can water exist as a liquid below the freezing point. Water that is not frozen below 0o C is called "super-cooled water". Saturation level of the air is directly related to the air's temperature. As air temperature increases, more water can remain in a gas phase. To maintain equilibrium the number of water molecules above the surface increases. And so at higher temperatures, it takes more w.v. to saturate the air. More w.v molecules exert a higher pressure. As temperature decreases, water molecules slow down and there is a greater chance for them to condense onto surfaces. Note that below zero degrees Celsius the curve splits, one for the saturation point above a liquid surface (liquid-vapor) and one for a surface of ice (ice - vapor). The first thing you might be wondering is how can water exist as a liquid below the freezing point. Water that is not frozen below 0o C is called "super-cooled water".

    15. Question Water will boil when SVP = atmospheric P Why is the boiling point lower in Denver, CO than in San Fransisco, CA? Denver is at a higher elevation, where the Atmospheric P is lower, therefore SVP is lower.Denver is at a higher elevation, where the Atmospheric P is lower, therefore SVP is lower.

    16. Relative Humidity (RH) RH = V.P. S.V.P. Does not tell you how much w.v. is in the air, just how close to saturation the air is Examples: If V.P. and S.V.P. are both 6 mb, RH = 6/6 = 100% RH often 100% at morning (dew) If V.P. is 6 mb and svp is 12 mb, RH = 6/12 = 50% RH often 50 % at midday

    17. Diurnal Variation of Relative Humidity RH varies with changing water vapor content or temperature Vapor content (VP) does not vary, temperature (SVP) does during day

    18. Questions When is the best time to water your lawn to minimize evaporation?   2. Why do your lips seem so dry in winter?  3. On a given day in winter, is the RH larger in a house or outside?   4. Is the evaporation rate greater inside the house or outside?  In the morning when the RH is largest. Because the amount of moisture in the air (V.P.) is very low due to the low temperature. Outside (VP does not vary, a lower outside air T means a lower SVP and therefore a higher RH). Inside (heating your home increases the evaporation rate). http://profhorn.meteor.wisc.edu/wxwise/relhum/rhac.html In the morning when the RH is largest. Because the amount of moisture in the air (V.P.) is very low due to the low temperature. Outside (VP does not vary, a lower outside air T means a lower SVP and therefore a higher RH). Inside (heating your home increases the evaporation rate). http://profhorn.meteor.wisc.edu/wxwise/relhum/rhac.html

    19. Dew-Point Temperature Dewpoint (dp) = temperature at which dew forms (saturation point) When air is cooled to dp, V.P. = S.V.P. (100% RH) If amount of moisture stays essentially constant during the day, dp is constant High dp = high wv content You can measure dp by measuring T of glass of water whilst adding ice, T at which condensation begins = dp This is determined by the current air temperature: the warmer the air, the greater the capacity. Unlike Relative Humidity, which is a measure of how near the air is to being saturated, dew-point temperature is a measure of its actual water vapour content. Because the dew-point temperature is directly related to the amount of water vapour in the air, and because it is easy to determine, it is one of the most widely used measures of humidity. (Lutgens, 2004)This is determined by the current air temperature: the warmer the air, the greater the capacity. Unlike Relative Humidity, which is a measure of how near the air is to being saturated, dew-point temperature is a measure of its actual water vapour content. Because the dew-point temperature is directly related to the amount of water vapour in the air, and because it is easy to determine, it is one of the most widely used measures of humidity. (Lutgens, 2004)

    20. Question Suppose the dew point of cold outside air is the same as the dew point of warm air indoors. If the door is opened, and cold air replaces some of the warm inside air, would the new relative humidity indoors be (a) lower than before, (b) higher than before, or (c) the same as before? Explain your answer. The dew point of the inside air would be unaffected by the mixing. However the inside temperature would drop and, as a consequence of that temperature change, (b), the inside relative humidity would increase. The dew point of the inside air would be unaffected by the mixing. However the inside temperature would drop and, as a consequence of that temperature change, (b), the inside relative humidity would increase.

    21. Dew Point and RH T and DP far apart RH is low Close together RH is high T = DP, saturated air RH = 100% Need to be careful with RH since air may be ‘dry’ A common misconception is that air with a high RH must have a higher wv content than air with a low RH Example: compare desert and polar air…

    22. Compare Desert and Polar Air High dew point = high water vapor content Low dew point = low water vapor content Polar air has higher RH, but desert air contains more wv, therefore it has a higher absolute humidity (AH) Compute RH from Fig. 4.5: 35 C SVP of 56 mb, dp temp of 5 C VP of 9 mb. RH = 9/56 = 16% Compute RH from Fig. 4.5: 35 C SVP of 56 mb, dp temp of 5 C VP of 9 mb. RH = 9/56 = 16%

    23. Dew-Point Temperature Variations Driest where? Wettest where? Driest: January - Interior; July – Desert SW Wettest: January - coasts; July – EasternDriest: January - Interior; July – Desert SW Wettest: January - coasts; July – Eastern

    24. Review Relative humidity (RH) does not tell us how much water vapor is in the air; rather, it tells us how close the air is to being __________ RH can change when the air’s water vapor content changes, or when air _________ changes With a constant amount of water vapor, cooling the air ________ RH and warming ________ it The dew-point temperature is a good indicator of the air’s water vapor content Saturated Temperature Increases, decreases Saturated Temperature Increases, decreases

    25. When Air T is High… Main source of body cooling is evaporation of perspiration (evaporative cooling) What happens when RH is low? When RH is high? Perspiration evaporates from the skin making us feel that the air temperature is lower than it actually is. Body moisture does not rapidly evaporate, we feel warmer.Perspiration evaporates from the skin making us feel that the air temperature is lower than it actually is.Body moisture does not rapidly evaporate, we feel warmer.

    26. RH and Human Discomfort Excessive water loss Heat exhaustion > 105 °F Heatstroke (130 °F) – failure of circulatory functions National Weather Service’s heat index (HI) – based on air temperature and relative humidity to give apparent temperature

    27. Questions 1.  On a warm, muggy day, the air is described as "close". What are several plausible explanations for this expression? 2.  Why are evaporative coolers used in Arizona, Nevada, and California, but not in Florida, Georgia, or Indiana? When air temperature and dew point are close together relative humidity is high. Relative humidity = 100% when they are the same. These units cool outdoor air by evaporation and blow it inside the building, causing a cooling effect much like the process when evaporating perspiration cools your body on a hot day. Fresh outside air is pulled through moist pads where it is cooled by evaporation and circulated through a house or building by a large blower. The hotter and drier the air, the more water that can be absorbed. In Fl, GA, IN the air is more moist than in the dry SW USA, making the process far less efficient. http://www.consumerenergycenter.org/homeandwork/homes/inside/heatandcool/evaporative_coolers.html http://www.taunton.com/finehomebuilding/pages/h00091.aspWhen air temperature and dew point are close together relative humidityis high. Relative humidity = 100% when they are the same. These units cool outdoor air by evaporation and blow it inside the building, causing a cooling effect much like the process when evaporating perspiration cools your body on a hot day.

    28. Measuring Humidity Psychrometer: two identical thermometers, bulb of one covered by small white cotton tube, soaked in water Air blown over both thermometers Plain thermometer measures air temperature Wet-bulb thermometer cools by evaporation, warmed by air. Relative humidity from Appendix D

    29. Wet-bulb Depression Large difference – drier the air, greater the evaporational cooling, R.H. is low Small difference – little evaporation is possible, air is close to saturation, R.H. is high

    30. Using the Sling Psychrometer Open the instrument Thoroughly wet the wick (white cotton), ensure no moisture on the dry bulb Rotate for 30 – 60 seconds (2-3 rev/s) Note wet and dry temperatures Close and use slide rule to calculate %RH Animation from USA Today.Animation from USA Today.

    31. Hygrometers Hygrometer = hygro (hydro) + meter = water + measure Hair hygrometer: length of hair changes with humidity Dew-point hygrometer: cool a surface until dew forms on it and measure surface T

    32. Fancier Hygrometers Electrical hygrometer: electrical resistance of carbon exposed to air varies with relative humidity IR hygrometer: measure brightness of source at two wavelengths having different absorptions by water vapor http://www.analyzer.com/Theory/moisture/moisture/moisture.htm http://www.analyzer.com/Theory/moisture/moisture/moisture.htm

    33. Dew and Frost Surface cools rapidly on clear calm nights Ground much colder than air above Air in contact with ground cools by conduction Cools to dp wv condenses as dew

    34. Questions 1. Dew/frost often form only close to the ground, e.g., not on a bush, why? 2. Dew and frost most often form on clear, calm nights, why? Radiation inversion Is likely in place due to nightime cooling. Radiational cooling and little turbulent mixing to mix cold air at the ground with warmer air aloft. (wintertime expression, "clear moon, frost soon.") Radiation inversion Is likely in place due to nightime cooling. Radiational cooling and little turbulent mixing to mix cold air at the ground with warmer air aloft.(wintertime expression, "clear moon, frost soon.")

    35. Question While driving from cold air (well below freezing) into much warmer air (well above freezing), frost forms on the windshield of the car. Does the frost form on the inside or outside of the windshield? How can the frost form when the air is so warm? The frost forms on the outside of the windshield because the outside surface is at a temperature below freezing. This fact is what makes the formation of frost possible. Saturated warm air is chilled to below freezing upon contact with the cold glass. Deposition or condensation with freezing occurs. The frost forms on the outside of the windshield because the outside surface is at a temperature below freezing. This fact is what makes the formation of frost possible. Saturated warm air is chilled to below freezing upon contact with the cold glass. Deposition or condensation with freezing occurs.

    36. Condensation Nuclei The process of condensation of vapor -> water to form a cloud drop is not that simple in the atmosphere NEED Condensation Nuclei to form cloud drops tiny particles in air created from/by: dust volcanoes factory smoke forest fires ocean salt They are most abundant in lower troposphere over urban areas They are quite small relative to a rain drop or cloud drop Occurs primarily when air is cooled (more likely for slow moving water vapor to come into contact with nuclei)

    37. Formation of Haze RH inc. at night as air cools WV condenses at RH as low as 75% if condensation nuclei available Size of droplets inc large enough to scatter light = haze Actually 2 types of Haze: dry haze - large/giant particles in the air (smoke, smog, dust) wet haze - H2O condenses onto hydroscopic CCN - can occur at RH's as low as 75%Actually 2 types of Haze: dry haze - large/giant particles in the air (smoke, smog, dust) wet haze - H2O condenses onto hydroscopic CCN - can occur at RH's as low as 75%

    38. Question Why do relative humidities seldom reach 100% in polluted air? Pollutants act as CN, abundance of CN causes water vapour to condense at low RH’s.Pollutants act as CN, abundance of CN causes water vapour to condense at low RH’s.

    39. Formation of Fog Forms as the RH increases to 100% - haze particles grow into fog particles near the ground Fog = cloud next to ground International definition: Visibility is less than 1 km NWS definition: Visibility is less than or equal to 6 miles and T-Td < 5°F Fog in polluted areas can be a health problem since it becomes acidic Dissipates as it is warmed by warm land 4 different kinds

    40. Formation of Radiation Fog Radiational cooling allows the temperature to drop to the dp point. Long night, calm wind required Can drain into valleys Ground cools faster than the air aboveGround cools faster than the air above

    41. Formation of Advection Fog Advection fog = warm moist air advects over a cold surface Occurs along pacific west coast when warm moist air from Pacific blows over cold CA Current Occurs along Gulf coast in winter when warm moist air blows onto land cooled by radiation Coast of Newfoundland, cold Labrador current parallel to warm gulf stream (2/3 days in summer)

    42. Advection Fog westerlies advect warm moist air over cold water heat is transferred from the warm, moist air to the cold water near the coast via conduction the parcel reaches saturation - forms fog, and is advected onshore NEED a light breeze for this process to occur Advection fog can be an important source of moisture for plant life along the CA coast - it rarely rains there during the summer months

    43. Upslope Fog Fog that forms as moist air flows up an elevated hill Air rises, expands, becomes cooler If cools to dp condensation occurs

    44. Formation of Steam Fog Water evaporates from warm surface; warm, moist air rises; mixes with cold air above; air cools to dp Air in steam fog not stable near the surface (warm air rises), looks wispy with no definite top

    45. Question On a cold morning, why can you sometimes see your breath? Similar to steam fog. Because the warm moist air from your mouth mixes with the cold air, the mixture cools to the dp and condensation forms.Similar to steam fog. Because the warm moist air from your mouth mixes with the cold air, the mixture cools to the dp and condensation forms.

    46. Distribution of Foggy Weather Where is it foggy? Pacific Coast Appalachian highland region New England Foggiest spot in the U.S.: Cape Disappointment, WA it's foggy for 2556 hours per year, or about 107 days. Other foggy locations: Mistake Island - off coast of Maine - 1580 hours per year Mt. Washington!! - experience fog on about 300 days each year!

    47. Question Explain why coastal California, the Appalachians, New England, and the Gulf Coast are so foggy - Occurs along pacific coast when warm moist air from Pacific blows over cold CA Current - Appalachians: moist air flows up a hill or mountain, upslope fog. - New England: Cold Labrador current lies parallel to warm Gulf Stream. Moist air from GS region drifts over the Labrador current - Gulf coast: It is especially common in the spring and fall or any time that there is a significant difference between water and air temperature. - Occurs along pacific coast when warm moist air from Pacific blows over cold CA Current - Appalachians: moist air flows up a hill or mountain, upslope fog. - New England: Cold Labrador current lies parallel to warm Gulf Stream. Moist air from GS region drifts over the Labrador current - Gulf coast: It is especially common in the spring and fall or any time that there is a significant difference between water and air temperature.

    48. Answer From Aguardo and Burt http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/atmospheric_moisture/geographic_patterns_fog.htmlFrom Aguardo and Burthttp://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/atmospheric_moisture/geographic_patterns_fog.html

    49. Fog Dispersal Few highways have warning systems Fog dispersal at airports Fog colder than freezing: seed with dry ice. Ice crystals grow and fall Most fog above freezing, not easily dispersed Other methods used, e.g. mixing, warming (evaporation), adding condensation nuclei

    50. Questions 1.  Explain why icebergs are frequently surrounded by fog. 2.  During a summer visit to New Orleans, you stay in an air-conditioned motel. One afternoon, you put on your sunglasses, step outside, and within no time your glasses are "fogged up." Explain what has apparently caused this. 3.  A January snowfall covers central Arkansas with 5 inches of snow. The following day, a south wind brings heavy fog to this region. Explain what has apparently happened. 1. The moist air over the ocean is nearly saturated. As it flows into the vicinity of an iceberg, the iceberg chills the air to its dew point, thus producing a fog. 1. The moist air over the ocean is nearly saturated. As it flows into the vicinity of an iceberg, the iceberg chills the air to its dew point, thus producing a fog.

    51. Review Dew, frost, and frozen dew generally form on clear nights when the temperature of objects at the surface cools below the air’s dew-point temperature Visible white frost forms in saturated air when the air temperature is at or below freezing. Under these conditions, water vapor can change directly to ice, in a process called ____________ ________ ________ act as surfaces on which water vapor condenses. Fog is a cloud resting on the ground Radiation fog, advection fog, and upslope fog all form as the air cools. Evaporation (mixing) fog, such as steam fog, forms as water evaporates and mixes with drier air Desposition Condensation nucleiDesposition Condensation nuclei

    52. Cloud Types Clouds are comprised of liquid droplets of various sizes and/or ice crystals They are characterized according to their height location in the atmosphere and their vertical development: High clouds Middle clouds Low clouds Vertically developed clouds More important than name: cloud appearance shows (in)stability. Cumulus: unstable environment (warm air rising); others more stable More important than name: cloud appearance shows (in)stability. Cumulus: unstable environment (warm air rising); others more stable

    53. Cloud Types NOTE: cloud names come from latin words: cirrus - curl stratus - layer cumulus - heap nimbus - violent rain

    54. High Clouds - Cirrus (Ci) Cirrus Clouds - high, thin wispy clouds up at jet stream level in the upper troposphere They are almost always comprised of ice Associated with fair weather (16,000-43,000ft)(16,000-43,000ft)

    55. High Clouds - Cirrostratus (Cs) Cirrostratus Clouds - high, thin, sheet-like clouds Ice crystals refract light to produce halos around the sun/moon fowl weather is often 12/24 hours away (16,000-43,000ft)(16,000-43,000ft)

    56. High Clouds - Cirrocumulus (Cc) Cirrocumulus Clouds - high clouds, rounded white puffs look like fish scales ‘mackeral sky’ (16,000-43,000ft)(16,000-43,000ft)

    57. Middle Clouds - Altocumulus (Ac) Altocumulus Clouds - shallow, puffy or wave-like in appearance Middle clouds are composed of water and/or ice appear the size of your thumbnail when holding your arm up to the sky (6500-23,000ft)(6500-23,000ft)

    58. Middle Clouds - Altostratus (As) Altostratus Clouds - grayish/blue-gray thin layer covering entire sky uniformly found ahead of storms the sun is visible through altostratus, but NO halo will be observed (6500-23,000ft)(6500-23,000ft)

    59. Low Clouds - stratus (St) Stratus Clouds - Uniform grayish cloud covering the entire sky (0-6500ft)(0-6500ft)

    60. Low Clouds - Nimbostratus (Ns) Nimbostratus Clouds - darker gray, "wet" looking low clouds they produce light/moderate precipitation over a large region (0-6500ft)(0-6500ft)

    61. Low Clouds - Stratocumulus (Sc) Stratocumulus Clouds - low, lumpy, puffy clouds in patches or rounded masses visually appear larger than altocumulus appear the size of your fist when holding your arm up to the sky (0-6500ft)(0-6500ft)

    62. Vertically Developed Clouds - Cumulus (Cu) Cumulus Clouds - Look like cotton balls/cauliflower in the sky sub categories of cumulus: cumulus humilis - slightly developed Cu cumulus congestus - moderately developed – see below: 

    63. Clouds with Vertical Development Cumulus (Cu) family Humilis, mediocris, congestus (in this order) http://www.tpub.com/content/aerographer/14269/css/14269_21.htmHumilis, mediocris, congestus (in this order) http://www.tpub.com/content/aerographer/14269/css/14269_21.htm

    64. Vertically Developed - Cumulonimbus (Cb) Cumulonimbus Clouds - thunderstorms develop from growing Cu can extend up to the troposphere can contain both water and ice contains precipitation (rain, snow, hail, etc) produce lightning and severe weather form a distinctive "anvil" cloud at the top of the storm

    65. Chart of Basic Cloud Types

    66. Other Unusual Clouds - Scud Scud - ragged low clouds beneath actual cloud base Often form due to turbulent mixing of air: warm air from the updraft cool air from the downdraft

    67. Other Unusual Clouds - Lenticular Clouds Lenticular Clouds - form as air flows over mountains look like pancakes, UFOs even

    68. Other Unusual Clouds - Pileus Pileus - forms as a growing thunderstorm deflects moist air up and over the top of the building cumulus congestus or cumulonimbus

    69. Other Unusual Clouds - Mammatus Mammatus - look like cow's udder visually very impressive usually form underneath Cb visual manifestation of sinking air, not rising air!

    70. Question The sky is overcast and it is raining. Explain how you could tell if the cloud above you is a nimbostratus or a cumulonimbus There are several clues that could be sought: (1) Large raindrops would indicate cumulonimbus; smaller drops, nimbostratus. (2) Intense, but variable rainfall would imply cumulonimbus; light or moderate, but steady rainfall, nimbostratus. (3) Strong, shifting surface winds would imply cumulonimbus; light steady surface winds or calmness would indicate nimbostratus. (4) A short period of rainfall would favor cumulonimbus; a persistent rainfall would favor nimbostratus. (5) Any accompanying lightning, thunder or hail would definitely imply cumulonimbus. There are several clues that could be sought: (1) Large raindrops would indicate cumulonimbus; smaller drops, nimbostratus. (2) Intense, but variable rainfall would imply cumulonimbus; light or moderate, but steady rainfall, nimbostratus. (3) Strong, shifting surface winds would imply cumulonimbus; light steady surface winds or calmness would indicate nimbostratus. (4) A short period of rainfall would favor cumulonimbus; a persistent rainfall would favor nimbostratus. (5) Any accompanying lightning, thunder or hail would definitely imply cumulonimbus.

    71. Question Which clouds are associated with each of the following characteristics: (a) lightning; (b) heavy rain showers; (c) mackerel sky; (d) mares’ tails; (e) halos; (f) light continuous rain or snow; (g) hailstones; (h) anvil top. The cloud characteristic-cloud type associations are as follows:         (a) lightning - cumulonimbus,         (b) heavy  rain showers - cumulonimbus,         (c) mackerel sky - cirrocumulus,         (d) mares’ tails - cirrus,         (e) halos - cirrostratus,         (f) light continuous rain or snow - nimbostratus or stratus,         (g) hailstones - cumulonimbus,         (h) anvil top - cumulonimbus. The cloud characteristic-cloud type associations are as follows:        (a) lightning - cumulonimbus,        (b) heavy  rain showers - cumulonimbus,        (c) mackerel sky - cirrocumulus,        (d) mares’ tails - cirrus,        (e) halos - cirrostratus,        (f) light continuous rain or snow - nimbostratus or stratus,        (g) hailstones - cumulonimbus,        (h) anvil top - cumulonimbus.

    72. Cloud Observations from Ground ASOS - Automated Surface Observing System ASOS - Automated Surface Observing System

    73. Satellite Observations of Clouds Two main orbits: Geostationary: positioned over the equator they orbit the earth at the same rate as the earths rotation this allows for a continuous view of the same location

    74. Satellite Observations of Clouds Polar orbit passes N-S over poles while Earth rotates eastward scan swath is about 300 km wide especially good for high latitiudes

    75. Satellite Sensors Visible basically a picture of the clouds - much like taking a picture with your camera Infrared tells you the temperature of what the satellite is sensing, whether its the ground or the tops of clouds very useful for determining the height of the cloud (low, middle, high)

    76. Satellite

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