Air Mass. 1. Air Mass : Large body of Air with similar temperature and humidity (or moisture) ; 4 types

Transcription

1 Air Mass 1. Air Mass : Large body of Air with similar temperature and humidity (or moisture) ; 4 types A. Continental-relatively dry air masses that form over land. B. Maritime: relatively humid air masses that form over the ocean C. Polar: cold air masses that form at high altitudes (Canada) D. Tropical: warm air masses that form at low latitudes (Gulf of Mexico)

2 Air Mass Cont d 1. Continental Polar Air Mass: cold and dry 2. Continental Tropical: Warm and Dry 3. Maritime Polar: cold and humid 4. Maritime Tropical: warm and humid 5. Arctic Air; cold and dry

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4 Front When air masses come together, the narrow zone of transition that forms between them is called an front

5 Cold Front Denser cold drier air advances while the warm humid air retreats

6 Warm Front Warmer humid air advances while the colder drier air retreats

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8 Factors in Thunderstorms Density of warm and cold air Convection: Warm air rises Cumulus clouds. 1. L. Mechanism to Trigger :Front, heating caused by the sun, or cooling aloft 2. I. Unstable atmosphere 3. M. Source of moisture L.I.M: Lift-Instability-Moisture

9 Thunderstorms continued Can be caused by air rising along either warm fronts or cold fronts Most intense usually from cold fronts greater temperature difference the greater chance of thunderstorms Short lived and in section of the city 3 stages cumulus, mature, and dissipating

10 Thunderstorms continued 3 stages cumulus, mature, and dissipating Cumulus stage: build upward and laterally, flat bases and towering tops (cauliflower look) Sever thunderstorms: very strong updraft

11 Thunderstorms continued Cumulus stage The first stage of a thunderstorm is the cumulus stage or developing stage. During this stage, masses of moisture are li9ed upwards into the atmosphere. The trigger for this li9 can be solar illumina<on, where the hea<ng of the ground produces thermals, or where two winds converge forcing air upwards, or where winds blow over terrain of increasing eleva<on. The moisture carried upward cools into liquid drops of water due to lower temperatures at high al<tude, which appear as cumulus clouds.

12 Thunderstorms continued Mature Stage In the mature stage of a thunderstorm, the warmed air con<nues to rise un<l it reaches an area of warmer air and can rise no farther. O9en this 'cap' is the tropopause. The air is instead forced to spread out, giving the storm a characteris<c anvil shape. The resul<ng cloud is called cumulonimbus incus. The water droplets coalesce into larger and heavier droplets and freeze to become ice par<cles. As these fall, they melt to become rain. If the updra9 is strong enough, the droplets are held alo9 long enough to become so large that they do not melt completely but fall as hail.

13 Thunderstorms continued Dissipa2ng stage In the dissipa<on stage, the thunderstorm is dominated by the downdra9. If atmospheric condi<ons do not support super cellular development, this stage occurs rather quickly, approximately minutes into the life of the thunderstorm. The downdra9 will push down out of the thunderstorm, hit the ground and spread out. This phenomenon is known as a downburst. The cool air carried to the ground by the downdra9 cuts off the inflow of the thunderstorm, the updra9 disappears and the thunderstorm will dissipate.

14 Thunderstorm Stages

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16 Thunderstorm

17 Cumulus Cloud

18 Mature Thunderstorm

19 How clouds form All air contains water vapor Warm saturated air has more vapor than cool saturated air Saturated air : some water vapor condenses into tiny water droplets=clouds Rising air is cooled by expansion, much like air coming out of a tire. As warm, moist air rises it expands and cools. As the moist air rises and cools to the dew point (temperature at which air is saturated with water vapor), it becomes saturated and condensation occurs. Cloud formation can only occur if the H20 vapor has something to "stick to." Dust particles in the atmosphere act as a condensation nuclei for the H20 vapor.

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21 How clouds form

22 High cloud Types of clouds Cirrus middle cloud Stratus low cloud Cumulus

23 Types of Clouds

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26 Warm-up: on front table Turn in homework describing how a thunderstorm is formed and drawings of the 3 types of clouds with your warm up. Honors Research paper on volcanoes and earthquakes is due 5/16/18 using turnitin.com, I have a guide and rubric for the paper Quiz this Wednesday: You will be able to use notes that you put on teacher supplied 3x5 card. Declaration of volcano and earthquake will be due by Wednesday either verbally or via

27 Warm-up What cloud is formed in a thunderstorm? Cirrus Name the 3 clouds we discussed in class: 1. Cirrus 2. Stratus 3. Cumulus What is an air mass? collec=on of air with same temp and moisture What causes a front? when 2 different air masses meet.

28 Supercell Thunderstorms Supercell thunderstorms occur when very strong updracs are balanced by downdracs. This can allow the storm to persist for many hours. In a supercell, a moist, unstable body of warm air may be forced to rise by an approaching cold front. The result is a strong, persistent updrac of warm moist air. Speeds in an updrac can be as fast as 90 miles per hour! The air cools as it rises. Water vapor condenses and forms cumulus clouds. When condensa=on occurs, heat (latent heat/energy ) is released and helps the thunderstorm

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31 Tornadoes

32 2017 Summer forecast

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34 Thunderstorms through out the world

35 Air Pressure: can be defined as the pressure of air in the earth's atmosphere. Occluded Front: when a cold front overtakes a warm front. Reading Weather map:

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37 Jet Stream Jet streams: are relatively narrow bands of strong wind in the upper levels of the atmosphere. The winds blow from west to east in jet streams but the flow often shifts to the north and south. Jet streams follow the boundaries between hot and cold air.

38 Jet Stream video

39 Lightning Air molecules are rubbing against each other creating charges much like static electricity is formed The warmer molecules moving upward form negative charges The cooler molecules moving downward form positive charges. When the charges grow large enough a spark is created.

40 * Lightning

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43 Lightning Video 2-3 min

44 Thunder When Lightning occurs it releases huge amounts of heat in a concentrated area. When the air molecules come in contact with intense heat they rapidly get excited and expand. Quiz this Wednesday: You will be able to use notes that you put on teacher supplied 3x5 card. Declaration of volcano and earthquake will be due by Wednesday either verbally or via

45 Thunder

46 Thunder Video 1-2 min