1. Topic IV “Meteorology”
Weather Studies

2. The Water Cycle

3. I. Moisture in the Atmosphere: the primary source of energy for the water cycle is the Sun. It unevenly heats Earth’s surface.
Phases of the Water Cycle:
Evaporation: liquid to gas. Requires energy (absorbed) making it a cooling process.
2. Condensation: gas (water vapor) to a liquid. Releases energy into the air making it a warming process.

5. 3. Transpiration: the releasing of water in the air by plants. 4
3. Transpiration: the releasing of water in the air by plants. 4. Precipitation: the falling of liquid or solid water from clouds. Ex. Rain, sleet, snow and hail

7. Accumulation - the process in which water pools in large bodies (like oceans, seas and lakes). Condensation - the process in which water vapor (a gas) in the air turns into liquid water. Condensing water forms clouds in the sky. Water drops that form on the outside of a glass of icy water are condensed water. (This term appears twice in the diagram.) Evaporation - the process in which liquid water becomes water vapor (a gas). Water vaporizes from the surfaces of oceans and lakes, from the surface of the land, and from melts in snow fields. Precipitation - the process in which water (in the form of rain, snow, sleet, or hail) falls from clouds in the sky. Subsurface Runoff - rain, snow melt, or other water that flows in underground streams, drains, or sewers. Surface Runoff - rain, snow melt, or other water that flows in surface streams, rivers, or canals. Transpiration - the process in which some water within plants evaporates into the atmosphere. Water is first absorbed by the plant's roots, then later exits by evaporating through pores in the plant.

8. B. Factors Affecting Evaporation Rate: http://www. vtaide
1. Temp.: as temperature increases, the evaporation rate increases
2. Humidity: as humidity inc. evap. rate decreases.
3. Wind: as wind inc. evap. rate inc.
4. Surface Area: as surface area inc. evap. rate increases.

9. C. Relative Humidity: a comparison between the amount of moisture in the air with the amount that the air can hold at that temp.
Dewpoint Temp.: the temp. at which condensation occurs.
* dew: drops of water forming on a cool surface.
* frost: water vapor freezes (sublimates) on a frozen surface.

10. 2. Sling Psychrometer: instrument used to determine the dewpoint temp
2. Sling Psychrometer: instrument used to determine the dewpoint temp. and relative humidity.
* Page 12 of ref. table to find dewpoint and relative humidity

11. D. Clouds: collection of tiny water droplets or ice crystals suspended in the atmosphere. (Cloud in a Bottle Demo)
Click on Picture Below
1. Cloud Formation:
a. Warm moist air rises.
b. Air cools below dewpoint temp. (condenses) and droplets form around condensation nuclei (dust/salts).

13. A. Barometer: instrument used to measure air pressure.
II. Air Pressure: the force/weight of air pushing on a surface. Air pressure pushes in all directions equally. Pg. 13 ref. Table.
Click on picture below
A. Barometer: instrument used to measure air pressure.
* As air pressure increases, the barometer rises.

14. PRACTICE (pg. 13 ESRT)
According to the Earth Science Reference Tables, an air pressure of inches of mercury is equal to:
a) 1017 mb
b) 1019 mb
c) 1021 mb
d) 1023 mb
Locate the chart in the Earth Science Reference Tables that shows pressure scales in millibars and inches. The right-hand column shows atmospheric pressure in inches of mercury. An air pressure of is halfway between 30.1 and Locating this point and reading over to the left-hand column yields an air preaure of 1,021 millibars.

15. B. Factors Affecting Air Pressure:
Temperature: as temp. increases, air pressure decreases.

16. 2. Altitude: as altitude increases, air pressure decreases.

17. 3. Humidity: as humidity increases, air pressure decreases.
“ Dry air weighs more then moist air”

18. Best conditions to hit a homerun?
Warm, moist day at a high elevation

19. C. Winds: caused by differences in air pressure
C. Winds: caused by differences in air pressure. The greater the difference (gradient) the stronger the winds.
Isobars: connect points of equal air pressure.
2. Anemometer: measures wind speed.
*the closer the isobars the greater the wind speed.

20. Winds: caused by differences in air pressure
Winds: caused by differences in air pressure. The greater the difference (gradient) the stronger the winds.

21. D. Local Breezes: smaller horizontal movement of air .
1. Sea breeze: air flows from the sea to the land.
*cooler air (high pressure) over the sea, flows towards warmer air (low pressure) over the land.

22. 2. Land breeze: air flows from the land to the sea.
Air over the land
cools at night (HIGH pressure) and flows towards the warmer air (LOW pressure) over the water.

23. E. Wind Direction: flow from regions of high to low pressure and named for the direction they come from.
1. Cyclone: (low pressure) winds blow counterclockwise towards the middle.
2. Anticyclone: (high pressure) winds blow clockwise and out.

24. Extreme Low Pressure

26. F. Global Winds: caused by the unequal heating of earth’s surface
F. Global Winds: caused by the unequal heating of earth’s surface. Page 14 ref. Table.
1. Diverging zones: cool, dry high pressure air sinks at the poles and 300 lat.
2. Converging zones: warm, moist low pressure air rises at the equator and 600 lat.

28. III. Air Masses: large masses of air that have a characteristic temp
III. Air Masses: large masses of air that have a characteristic temp. and moisture of their source region. Page 13 ref. table.
A. Source Regions:
1. Maritime: formed over water. (moist)
2. Continental: formed over land. (dry)
3. Polar: cool air from high latitudes
4. Tropical: warm air from low latitudes.
Click on Picture

29. IV. Front: the boundary that separates two different air masses. Pg
IV. Front: the boundary that separates two different air masses. Pg. 13 ref.
A. Types of Fronts:
1. Cold Front: dense cold air forces warm moist air upward creating heavy precipitation for short periods of time at the frontal boundary.

30. 2. Warm Front: warm air slowly rises over cold air producing long periods of light precipitation ahead of the frontal boundary.

31. 3. Occluded Front: a fast moving cold front over takes a slower warm front causing clouds and precipitation.

32. 4. Stationary Front: cold and warm air masses near each other with neither advancing causing long periods of light precipitation.

33. B. Synoptic Weather Maps: show weather conditions on a national or global basis.
1. Storm Tracks: most storm systems are pushed by planetary winds from SW to NE across the U.S.

34. V. Severe Weather:
A. Hurricanes: a large low pressure rotating storm of tropical origin.
*they get their energy from warm water. Once they hit land they lose energy.

35. Hurricane Eye

36. B Tornadoes: caused by the collision of warm, moist air with cold, dry air. Winds can exceed 370 mph.
C. Storm Safety:
1. Stay indoors
2. Store food/water
3. Have batteries/flashlights
4. Have a radio