Review from textbook, pages D2-D23
VOCABULARY
| air mass | A huge body of air which all has similar temperature and moisture | |
| air pressure | Particles of air pressing down on the Earth's surface | |
| atmosphere | The layer of air that surround our planet | |
| barometer | An instrument that measures air pressure | |
| cirrus | Wispy, high-altitude clouds that are made up of ice crystals | |
| cumulonimbus | Towering, dark rain clouds with a nimbus, or halo, of gray-white | |
| cumulus | Puffy cotton-ball clouds that begin to form when water droplets condense at middle altitudes | |
| front | The border where two air masses meet | |
| greenhouse effect | The warming of Earth caused by the atmosphere trapping thermal energy from the sun | |
| humidity | The amount of water vapor in the air | |
| hygrometer | A tool to measure moisture in the air | |
| stratosphere | The layer of atmosphere that contains ozone and is located above the troposphere | |
| stratus | Dark gray colds that form a low layer and sometimes bring light rain or snow showers | |
| troposphere | The layer of atmosphere closest to Earth |
CRITICAL THINKING
1. You hear on a weather report that a cold front is coming. What weather changes can you expect?
Wind speed, wind direction, and air pressure all change as a front approaches. the warm air being pushed up into the atmosphere will cool, and water vapor will condense to form clouds. Rain, perhaps even thunderstorms, will occur. After the front passes, skies will clear and temperatures will decrease.
2. Suppose you watch the weather report each day for five days. Each day the average temperature is the same and the air pressure doesn't change. What could be happening?
You could be under the influence of a stationary front or you may be in the middle of a slowly moving air mass. It appears that no fronts have approached during the five-day period.
3. How is a number description of wind speed different from a word description of wind speed?
A number description is usually more precise and accurate than a word description that uses adjectives, nouns, and adverbs.
4. Suppose you will measure weather conditions over the next five days. What equipment will help you measure?
You should use a thermometer for measuring temperature, a barometer for air pressure, a hygrometer for moisture in the air, an anemometer for wind speed, and a wind vane for wind direction.
5. Describe a warm front, and tell what happens as a warm front moves through an area.
A warm front occurs in regions where a warm air mass catches up with a cold air mass. As the front develops, cirrus clouds slowly change to stratus clouds. Cumulus clouds become lower and thicker, forming cumulonimbus clouds, which bring the rain.
6. Why are weather forecasts sometimes incorrect?
Fronts can form and move quickly. These changes can affect local weather.
7. What factors affect humidity?
Humidity is affected by air temperature and the region over which an air mass forms.
8. How does the sun affect weather?
Weather begins with the sun, which provides energy for making weather. The amount of the sun's energy reaching Earth is not the same everywhere. More energy reaches the equator than the poles. this uneven heating s part of what causes air to move and what makes weather.
9. What are the similarities and differences between an air mass and a front?
Air masses and fronts both determine the weather. Air masses are oceans of air that are similar in temperature and humidity; fronts are where tow or more air masses meet.
WEATHER INSTRUMENTS
| Weather Instrument | What Does It Measure? | Metric Unit of Measure | Customary Unit of Measure | |||
| thermometer | temperature | Degrees Celsius (C) | Degrees Fahrenheit (F) | |||
| hygrometer | humidity | |||||
| wind vane | wind direction | north, south, east, west | north, south, east, west | |||
| anemometer | wind speed | kilometers per hour (kph) | miles per hour (mph) | |||
| rain gauge | precipitation | centimeters (cm) | inches (in.) | |||
| barometer | air pressure | pascal (Pa) or newton/m2 | inches of mercury or in millibars (mb) |
WEATHER SYMBOLS
| thermometer |  |
cold front |  |
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| hygrometer |  |
warm front |  |
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| wind vane |  |
stationary front |  |
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| anemometer |
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rain |  |
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| barometer |
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snow |  |
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| weather map |  |
