Study GuideTest 12/8

Topics Include:Relative Humidity

Dew PointCloud Formation

Air MassesFronts

Scientific Method

Make Sure You Understand:

Relative humidity is the amount of moisture (water vapor) in the air compared to the amount of moisture the air can hold at that temperature.

Dew Point is when air cools to the temperature at which air is saturated.

Assuming the amount of water vapor in the air stays the same…

•If the temperature increases, then the relative humidity decreases.

•If the temperature decreases, then the relative humidity increases.

What is a cloud made of?

• A cloud is made of water droplets condensed on dust particles in the air

DustParticleWater Vapor Water Vapor

Be able to answer the following:If you see these clouds in the sky what weather can you expect?

Name of Cloud Appearance Effect

 1. Cumulus

 White, puffy, cotton ball clouds

 Fair weather. Nice day outside.

 2. Cirrus

 Feathery, wispy clouds.  Made of ice crystals!

 Fair at present, BUT rain in 24 – 48 hours (a day or two).  Warns of a warm front approaching.

 3. Stratus  

 Flat layers of gray clouds Brings gentle steady rain.

 Forms in a warm front. 

 4. Cumulonimbus  

 Thunderhead!

Dark flat bottoms building into anvil shaped tops

 Thunderstorms! Heavy rain, thunder, lightning, and possible hail. Forms in cold front.

Air MassesA. mPB. cP and/or cAC. mPD. cTE. mTF. mT

G. What is the origin of each of the 3 mT air masses?

The Pacific Ocean, the Gulf of Mexico, and the Atlantic Ocean

Air MassesAn air mass is named for it’s temperature and moisture level.

When two air masses meet the warm air mass will rise and the cool air mass will sink.

Continental

Maritime

Polar

Tropical

Dry

Wet

Cold

Warm

Cold Air Masses• A Continental Polar (cP) air mass brings cool,

dry weather in the summer.

• A Continental Polar (cP) air mass brings extremely cold weather in the winter.

• A Maritime Polar (mP) air mass brings cool, foggy weather in the summer.

• A Maritime Polar (mP) air mass brings cool weather with rain and snow in the winter.

Warm Air Masses• A Continental Tropical (cT) air mass brings clear,

dry, and hot weather in the summer.

• A Continental Tropical (cT) air mass brings warm and dry weather in the winter.

• A Maritime Tropical (mT) air mass brings hot, humid weather, with possible hurricanes and thunderstorms in the summer.

• A Maritime Tropical (mT) air mass brings mild, often cloudy weather in the winter.

FrontsFronts are the boundary between different air masses.

• Cold fronts create short, heavy, violent periods of rain followed by cool fair weather

• Warm fronts occur when warm air rises and condenses into long areas of clouds which bring gentle rain or snow followed by warmer weather

• Stationary fronts create clouds and fog at the site of the front and can bring days of rain or snow

• Occluded fronts occur when warm air is cut off from the ground which can bring heavy wind and precipitation

Warm front

(red)

Make sure you know:

1. Which symbol belongs to which front.2. The color of each front symbol.3. The type of weather does each front bring.

Occluded front

(purple)

Cold front

(blue)

Stationary front

(red and blue)

Think about it…• Would a farmer prefer the rain from a warm front or a

cold front to come through his area during the growing season?

• Explain why..• Suppose you are planning an outdoor activity for

tomorrow afternoon. You hear on the weather that a front is coming through tonight. With the understanding that you want to be outside tomorrow, which of the 4 fronts we learned about would you rather have come through?

• Fully explain why.

A Farmer Would Prefer A..WARM FRONT!

because…

Warm Fronts are good for farmers because…

• Gentle, prolonged rain that can soak in soil and water plants

• It will NOT erode the soil

• It will NOT damage plants

• It is warm after the front

Cold Fronts are bad for farmers because…

• Short, violent rain that may not soak into the soil to water plants

• Violent rain that erodes soil

• It will damage plants (hail)

• It is cold after that front, which may kill the plants

Scientific Method (know them in order)

• The Steps of the Scientific Method:

• People In Hawaii Eat Coconuts!

• Problem• Information• Hypothesis• Experiment• Conclusion

• During the experiment you must remember:

• Madison Police Department!

• Materials• Procedures• Data