| A | B |
|---|
| Air mass | A large body of air that has the same temperature, pressure, and humidity throughout. |
| Air pollutants | Harmful substances added to the air by human acitivities. |
| Air pressure | The force with which air presses down on Earth. |
| Altitude | The height of a place above sea level. |
| Axis | An imaginary line through Earth's center around which Earth turns. |
| Barometer | A device used to measure atmospheric pressure. |
| Climate | The general weather of a place over a long period of time. |
| Cloud | A large mass of tiny condensed water droplets. |
| Cold front | The boundary that forms when a cold air mass moves into a warm air mass. |
| Condensation | The change from a gas or vapor phase to a liquid phase. |
| Degree | The unit used to measure temperature |
| Celsius | A temperature scale where water freezes at 0 degrees and boils at 100 degrees. |
| Fahrenheit | A temperature scale where water freezes at 32 degrees and boils at 212 degrees. |
| Density | The mass of a substance divided by its volume. |
| Dew point | The temperature at which water vapor starts condensing into water. |
| Doldrums | The area around the equator where there is very little wind. |
| Evaporation | The change from a liquid phase to a gas or vapor phase. |
| Front | The boundary between two air masses, and where the most active weather occurs. |
| High | An area of high air pressure. |
| Humidity | The amount of water vapor in the air. |
| Inversion | A condition that occurs when the air at the surface is cooler than the air above it. |
| Latitude | The measure of a place's distance north or south of the equator. |
| Equator | An imaginary line around the circumference of the earth, midway between the poles. |
| Low | An area of low air pressure. |
| Phase | One of the three forms that matter may take; solid, liquid, or gas. |
| Precipitation | Condensed water that falls from the sky; rain, snow, sleet, and hail. |
| Prevailing winds | Winds that always blow in the same direction, forming the pattern of the Earth's winds. |
| Thunderstorm | A violent local rainstorm accompanied by lightning. |
| Temperate | A climate that has warm summers, cold winters and precipitation throughout the year. |
| Temperature | A measure of the amount of heat energy contained in a substance. |
| Tornado | A violent, funnel-shaped wind. |
| Warm front | The boundary that forms when a warm air mass moves into a cold air mass. |
| Water vapor | Water in the gaseous phase or state. |
| Weather | The condition of the atmosphere at a particular place and time. |
| Sea Breeze | A wind blowing from the water to the land. |
| Land Breeze | A wind blowing from the land to the water. |
| Wind vane | A device used to find the direction from which the wind is blowing. |
| Anemometer | A device used to measure the speed the wind is blowing. |
| Hygrometer | A device used to measure the relative humidity. Also called a psychrometer. |
| Relative humidity | A measure of the amount of water vapro that air contains relative to the |
| Wind direction | Where wind is blowing from. A north wind comes from the north and moves south. |
| Cirrus | A high altitude, thin cloud made of ice crystals. |
| Cumulus | A cloud that looks like puffs of cotton, usually flat on the bottom. Dark gray ones |
| Stratus | Low altitude cloud layers usually associated with stormy weather. |
| Continental | Source of a dry air mass. |
| Maritime | Source of a moist air mass. |
| Polar | Source of a cold air mass. |
| Tropical | Source of a warm air mass. |
| Thermometer | A device used to measure air temperature. |
| Weather map | A record of all the information from weather stations that weather forecasters use to predict the weather. |
| Radiation | Electromagnetic energy released by the sun that provides energy to the earth. |
| Trade winds | Prevailing winds near the equator. Those north of the equator move from the northeast to the southwest. |
| Westerlies | Prevailing winds in a wind belt north of the equator which blow from the southwest to the northeast. |
| Fog | Moisture that condenses in the air near the ground. |
| Rain | Moisture that condenses in clouds and falls towards earth. |
| Snow | Moisture that condenses, then freezes within clouds and falls towards earth. |
| Dew | Moisture that condenses on surfaces such as grass, pavement or cars. |
