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Regional Gliding School Cloud Formation Clouds form when invisible water vapour that is present in the air changes into its visible form as water droplets.

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Presentation on theme: "Regional Gliding School Cloud Formation Clouds form when invisible water vapour that is present in the air changes into its visible form as water droplets."— Presentation transcript:

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3 Regional Gliding School Cloud Formation Clouds form when invisible water vapour that is present in the air changes into its visible form as water droplets or ice crystals, via condensation or sublimation. This occurs when: the relative humidity is high, when condensation nuclei are present, and when there is a cooling of air.

4 Regional Gliding School Lifting Agents  Orographic lift  Air blowing against a range of hills or mountains is forced upward into a region of lower pressure, expands and cools. Condensation will occur when the dew point is reached.  Frontal lift  A mass of warm air is forced aloft and rises over the cold air. The rising warm air cools by expansion and clouds are formed.  Convection  As the sun heats the earth unevenly, rising currents will occur. This is convection. The rising air expands and cools. This produces condensation and cumuliform cloud forms at the top of the column of air. Further ascent and cooling causes rain.

5 Regional Gliding School Lifting Agents  Convergence -  Air is forced into a region, as at the center of a low, convergence is occurring. The excess air is forced to rise, as it rises it expands and cools. When the condensation level is reached, cloud form.  Turbulence  As wind blows over an uneven or rough surface or when uneven heating occurs, vertical currents are created. Air in the upward motion cools by expansion and if enough moisture is there condensation occurs. This results in cumulus cloud.

6 Regional Gliding SchoolPrecipitation When water droplets (visible as a cloud) grow sufficiently in size and weight to fall due to gravity.

7 Regional Gliding School Forms of Precipitation  Drizzle, rain, freezing drizzle, freezing rain  Hail, snow pellets (soft hail)  Snow  Ice prisms  Ice pellets

8 Regional Gliding School Drizzle, freezing drizzle, snow Snow or rain (continuous) Ice pellets (continuous) Hail, ice pellet showers Snow shower, rain showers Snow or rain (intermittent) Ice prisms PRECIPITATIONCLOUD TYPE Stratus and stratocumulus Thick altostratus and nimbostratus Thick altostratus and stratocumulus Altocumulus, heavy cumulus, cumulonimbus Cumulonimbus Any rain cloud (below freezing) No clouds necessary Snow pelletsHeavy cumulus

9 Confirmation Stage NOTE: You must use the buttons in the Confirmation Stage

10 Regional Gliding School A B C D Orographic Lift Frontal Lift Let's try a few review questions on Meteorology: Question #1 - A mass of warm air is forced aloft and rises over the cold air. The rising warm air cools by expansion and clouds are formed. This phenomena is known as. Convection Convergence Meteorology Clouds, Precipitation & Fog

11 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

12 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

13 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

14 That answer is correct. Let's move on...

15 Regional Gliding School A B C D Stratocumulus Stratus Let's try a few review questions on Meteorology: Question #2 - What cloud will produce continuous rain? Nimbostratus Cirrostratus Meteorology Clouds, Precipitation & Fog

16 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

17 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

18 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

19 That answer is correct. Let's move on...

20 Regional Gliding School Fog is a cloud, usually stratus, in contact with the ground. It forms when the air is cooled below its dew point, or when the dew point is raised to the air temperature through the addition of water vapour.

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22 n clear skies n moist air n light winds (2-5 knots) Usually forms on clear nights. Conditions that favor the formation of radiation fog are: The ground cools losing heat through radiation. The air in direct contact with the earth’s surface is cooled. If this air is moist and the temperature is lowered to the dew point, fog will form.

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24 Regional Gliding School Forms when warm moist air moves over a cold surface.

25 Regional Gliding School scan AdvectionFog WARM MOIST AIR 9 COLD LABRADOR CURRENT

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27 Regional Gliding School Caused by the cooling of air due to expansion as it moves up a slope. A light upslope wind is necessary.

28 Regional Gliding School scan example of upslope fog MSL YQR Regina YBR Brandon YPG Portage La Prairie YWG Winnipeg Stable, moist easterly flow

29 Regional Gliding School Forms when cold air passes over a warm water surface. Evaporation of the water into the cold air occurs until the air becomes saturated. The excess water vapour condenses as fog.

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32 Regional Gliding School Often found near fronts. Warm front fogs are the most extensive and are caused by the cold air becoming saturated by evaporation from rain falling from the warm air. It is also known as precipitation- induced fog.

33 Regional Gliding School FRONTAL FOG SATURATION OF COLD AIR BY EVAPORATION OF FALLING PRECIPITATION FOG NS ST 32

34 Regional Gliding School Caused by the addition of moisture to the air through evaporation of precipitation.

35 Regional Gliding School At very low temperatures, the air may become full of ice crystals. The ice crystals, which formed by sublimation, may suddenly appear when an aircraft engine has been started (the exhaust contains water vapour, condensation nuclei and the engine create mixing).

36 Confirmation Stage NOTE: You must use the buttons in the Confirmation Stage

37 Regional Gliding School A B C D Radiation fog Advection fog Let's try a few review questions on Meteorology: Question #3 - What fog forms when warm moist air moves over a cold surface? Upslope fog Frontal fog Meteorology Clouds, Precipitation & Fog

38 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

39 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

40 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

41 That answer is correct. Let's move on...

42 Regional Gliding School A B C D Radiation fog Precipitation-induced fog Let's try a few review questions on Meteorology: Question #4 - What fog forms when cold air passes over a warm water surface. Evaporation of the water into the cold air occurs until the air becomes saturated. The excess water vapour condenses as fog. Upslope fog Steam fog Meteorology Clouds, Precipitation & Fog

43 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

44 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

45 I’m afraid that answer is incorrect Let's try again... Flying Scholarship Program

46 That answer is correct. Let's move on...

47 Regional Gliding School Congratulations!! You have now completed the Clouds, Precipitation & Fog lesson of the Meteorology Module. Of course, this lesson is always available to you for future reference if required. You are now ready to move along to the next Meteorology lesson you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam. Good Luck! Meteorology Clouds, Precipitation & Fog


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