1. Study Guide Test 12/16 Topics Include: Relative Humidity Dew Point Cloud Formation Air Masses Fronts

2. 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. When the air is Saturated, it has 100% relative humidity. 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.

3. What is a cloud? A cloud is made of water droplets. Clouds form when warm air rises and cools

4. Be able to answer the following: Name of CloudAppearanceEffect 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 cloudsBrings 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.

5. Key Terms Precipitation - water that falls to the Earth’s surface as rain, snow, sleet, or hail Condensation - process in which water vapor cools and turns to liquid Weather- condition of the atmosphere at a certain time and place Humidity- the amount of moisture in the air

6. Key Terms, continued Anticyclone- area of high pressure where air moves apart and sinks Cyclone- area of low pressure where air masses meet and rise Dew Point- the temperature at which a gas condenses into a liquid

7. Measuring Weather Anemometer- measures wind speed Barometer - measures air pressure Radar - locates precipitation Thermometer - measures air temperature Windsock - measures wind direction

9. Air Masses A. mP B. cP and/or cA C. mP D. cT E. mT F. 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

10. Air Masses An 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

12. Air Masses An air mass is a body of air. A Continental Polar (cP) air mass brings cold, dry weather. A Maritime Polar (mP) air mass brings cold, moist (wet) weather. A Continental Tropical (cT) air mass brings dry and warm weather. A Maritime Tropical (mT) air mass brings warm, moist (wet) weather.

13. Fronts Fronts 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

14. 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)

15. Topics to Review Dew Point Lab – Words to know: Dew Point, Saturated, Condensation, Water Vapor High Pressure System Low Pressure System