1. Dec.19,2018 You need: Clean paper / pencil Water cycle filled in
Warm Up:
Start with evaporation and list the steps of the water cycle.
I CAN: determine how heat, water, and air interact to create air masses and fronts.
Dec.19,2018

2. Water in the Atmosphere

3. Earth is called the “Water Planet”
71% of the earth’s surface is covered by water.
Water is essential for LIFE on earth.

4. Water on earth’s surface is easy to see…
Oceans
Lakes
Rivers
Glaciers
But what about water in earth’s atmosphere???

5. Water in the atmosphere
It’s less obvious than surface water, but there are many signs of water in the atmosphere:
Rain, Snow, Drizzle
Clouds & Fog
Hot days that feel “muggy” or “humid”
Dew on the grass in the morning

6. Water Cycle
The movement of water between the atmosphere and earth’s surface is the water cycle.

7. How does water get into the air?
EVAPORATION – is the process where liquid water molecules escape into the air as water vapor.
3 things affect how quickly water evaporates:
1) Temperature
2) Wind
3) Humidity of the air

8. How much water can air hold?
HUMIDITY is the measure of how much water vapor is in the air.
TEMPERATURE affects how much water vapor the air can hold…
Warm Air
Cold Air
holds MORE water vapor.
holds LESS water vapor.
That’s why air feels more “HUMID” on hot days!

9. What is the “Dew Point”?
As air cools, the amount of water vapor it can hold decreases.
At a certain temperature, the water vapor in the air will CONDENSE back into water droplets or ice.
This temperature is the “DEW POINT”.

10. What is the “Dew Point”?
So, when the air temperature equals the “Dew Point” temperature, the air cannot hold any more water.
That means relative humidity is 100%!

11. Ever wondered about why the grass (or a car windshield) is wet in the morning?
Overnight, the temperature dropped below the “dew point” temperature, and the water in the air condensed into water droplets on the grass.

12. Climate vs Weather Global vs Local winds
LARGE scale = overall pattern, trend
small scale = daily, weekly, small times
Global vs Local winds
LARGE scale = Over the entire Earth
small scale = tiny area…usually land beside water.

13. Global winds 1 2 3 4 5 Polar easterlies Prevailing westerlies
Horse latitudes 4
Trade winds 5
Equator / Doldrums

14. United States of America

15. Coriolis Effect – the effect on the air caused by the rotation of the earth.

16. Watch the BrainPop video on “Humidity”. Write down 3 things you learned.

17. Air Masses & Fronts

18. What is an AIR MASS? WARM COLD WET DRY
An air mass is a huge body of air that influences weather.
Scientists classify air masses based on:
TEMPERATURE and HUMIDITY
WARM
COLD
WET
DRY

19. Air Masses are named based on where they FORMED…
= TROPICAL
= POLAR
= MARITIME (means sea… wet)
= CONTINENTAL (means land… dry)
WARM
COLD
WET
DRY

20. How are Air Masses named?
WET
DRY
MARITIME
TROPICAL
CONTINENTAL
TROPICAL
WARM
MARITIME
POLAR
CONTINENTAL
POLAR
COLD

21. North American Air Masses
MARITIME POLAR
CONTINENTAL POLAR
MARITIME POLAR
MARITIME TROPICAL
MARITIME TROPICAL
CONTINENTAL TROPICAL

22. How do these air masses move?
MARITIME POLAR
CONTINENTAL POLAR
MARITIME POLAR
Jet Stream
That’s why weather generally moves WEST to EAST
in the U.S.
Jet Stream
Prevailing Westerlies
Prevailing Westerlies
MARITIME TROPICAL
MARITIME TROPICAL
CONTINENTAL TROPICAL

23. What happens when air masses meet?
Air masses don’t mix easily.
The line between air masses is called a front.

24. COLD FRONTS

25. WARM FRONTS

26. Watch the BrainPop video on “Weather” and write down 2 things you learned.

27. Use your textbook (pg.133-135) to fill out the chart.

28. Compare/Contrast Chart - Types of Fronts
How it Forms
Type of Weather
Cold
A fast-moving cold air mass overtakes a warm air mass.
Clouds form.
If warm air is humid, rain/snow may fall.
Possible thunderstorms.
Warm Front
Stationary Front
Occluded Front

29. Compare/Contrast Chart - Types of Fronts
How it Forms
Type of Weather
Cold
A fast-moving cold air mass overtakes a warm air mass.
Clouds form.
If warm air is humid, rain/snow may fall.
Possible thunderstorms.
Warm Front
A warm air mass overtakes a slow-moving cold air mass.
Scattered clouds.
Light rain or snow.
May last several days.
Stationary Front
Occluded Front

30. Compare/Contrast Chart - Types of Fronts
How it Forms
Type of Weather
Cold
A fast-moving cold air mass overtakes a warm air mass.
Clouds form.
If warm air is humid, rain/snow may fall.
Possible thunderstorms.
Warm Front
A warm air mass overtakes a slow-moving cold air mass.
Scattered clouds.
Light rain or snow.
May last several days.
Stationary Front
Cold and warm air meet, but neither can move the other. Creates “standoff”
Rain, snow, clouds, or fog that may last for days.
Occluded Front

31. Compare/Contrast Chart - Types of Fronts
How it Forms
Type of Weather
Cold
A fast-moving cold air mass overtakes a warm air mass.
Clouds form.
If warm air is humid, rain/snow may fall.
Possible thunderstorms.
Warm Front
A warm air mass overtakes a slow-moving cold air mass.
Scattered clouds.
Light rain or snow.
May last several days.
Stationary Front
Cold and warm air meet, but neither can move the other. Creates “standoff”
Rain, snow, clouds, or fog that may last for days.
Occluded Front
A warm air mass is caught between 2 cooler air masses. Warm air mass is pushed up.
Temperature gets cooler.
Clouds and rain may form.

32. Surface Map (Fronts & Precipitation)
Warm Front H
High Pressure
Occluded Front L
Low Pressure
Cold Front
Stationary Front

33. Temperature Map

34. H L What will happen to the weather in Little Rock?
Which direction is the warm front moving? L H
12°C
19°C
14°C
20°C
25°C
Tuesday Weather
Little Rock, AR
Clouds & Rain
Warmer = 21°C
Wednesday Weather
Little Rock, AR
Partly Sunny
Warmer = 26°C
Monday Weather
Little Rock, AR
Sun & clear skies
Cool = 15°C
28°C
21°C
26°C
15°C
30°C
Warm Front H
High Pressure
Occluded Front L
Low Pressure
Cold Front
Stationary Front

35. Which direction is the cold front moving?
What will happen to the weather in Nashville?
10°C
8°C
18°C
10°C
11°C
Thursday Weather
Nashville, TN
Partly Sunny
Warm = 20°C
Saturday Weather
Nashville, TN
Sunny
Cool = 10°C
Friday Weather
Nashville, TN
Thunderstorms
Cooler = 15°C
10°C
20°C
15°C
Warm Front H
High Pressure
Occluded Front L
Low Pressure
Cold Front
Stationary Front

36. BrainPop Log in: carrington1 Password: cougars
Watch the WEATHER video and write what you learn.
Watch WIND, HUMIDITY, CLOUDS – video for each. Write two things you learn from each.