Transcript Weather
Weather Weather • Weather refers to the state of the atmosphere at a specific time and place. • The one thing that you can talk to anybody about • If you don’t like the weather in Texas just wait around it will change Weather Components • temperature, wind, clouds, humidity and precipitation, air pressure and air masses • List the component and tell what it is and how it affects the weather on a daily basis Temperature • Temperature is a measure of the energy of air molecules • High temperature means fast movement, low temperature means slower movement Wind • Wind is air moving in a specific direction • As the Sun warms the air it expands and becomes less dense and low pressure. • Cooler air is more dense and sinks with higher pressure • Wind results because air moves from high pressure to low pressure (cool to warm) Wind Measurement • Wind can be measured with a tool called an anemometer Clouds • A visible body of water droplets or ice particles suspended in the atmosphere Cloud Classification Precipitation • Water that falls from the clouds • Air temperature determines the form of precipitation that falls • 4 main types of Precipitation: Rain, Sleet, Snow and Hail Types of Precipitation Rain Sleet Snow Hail Humidity • Humidity is the amount of water vapor present in the air • Warmer air contains more water vapor than cooler air • Which has more water vapor? Humidity cont’d • Relative humidity is the measure of the amount of water vapor present compared to the amount needed for saturation • Dew point is the temperature at which the air is saturated and condensation forms • The closer the temperature is to the dew point, the more humidity there is Humidity Measurement • Humidity can be measured with a tool called a psychrometer Pressure and Air Masses • An air mass is a large body of air that has properties similar to where it developed • For example, one that forms over land will be dry. One that forms in the tropics will be warm • As these air masses move, weather changes occur • High pressure systems are usually fair and dry • Low pressure systems are usually cloudy and wet Worldwide Air Mass Map c=continental m=maritime p=polar t=tropical e=equatorial Isobars Lines that connect areas of equal pressure Sketch this picture Fronts • A front is a boundary between two air masses of different density, moisture or temperature • Cold fronts occur when cold air moves towards warm air. They usually bring thunderstorms Front’s Cont’d • Warm fronts form when warmer air moves over colder air. These usually form hours or days of wet weather Fronts Cont’d • Stationary fronts occur when the boundary between two fronts stops advancing. They may remain in place for several days