WeatherWeather

WeatherWeather• Weather refers to the state of the Weather refers to the state of the

atmosphere at a specific time and atmosphere at a specific time and place.place.

• The one thing that you can talk to The one thing that you can talk to anybody anybody aboutabout

• If you don’t like the weather in Texas If you don’t like the weather in Texas just wait around it will changejust wait around it will change

Weather ComponentsWeather Components

• temperature, wind, clouds, humidity temperature, wind, clouds, humidity and precipitation, air pressure and and precipitation, air pressure and air massesair masses

• List the component and tell what it is List the component and tell what it is and how it affects the weather on a and how it affects the weather on a daily basisdaily basis

TemperatureTemperature

• Temperature is a measure of the Temperature is a measure of the energy of air moleculesenergy of air molecules

• High temperature means fast High temperature means fast movement, low temperature means movement, low temperature means slower movementslower movement

WindWind

• Wind is air moving in a specific directionWind is air moving in a specific direction

• As the Sun warms the air it expands and As the Sun warms the air it expands and becomes less dense and low pressure. becomes less dense and low pressure.

• Cooler air is more dense and sinks with Cooler air is more dense and sinks with higher pressurehigher pressure

• Wind results because air moves from high Wind results because air moves from high pressure to low pressure (cool to warm)pressure to low pressure (cool to warm)

Wind MeasurementWind Measurement

•Wind can be Wind can be measured with measured with a tool called an a tool called an anemometeranemometer

CloudsClouds

• A visible body of water droplets or A visible body of water droplets or ice particles suspended in the ice particles suspended in the atmosphere atmosphere

Cloud ClassificationCloud Classification

PrecipitationPrecipitation

• Water that falls from the cloudsWater that falls from the clouds

• Air temperature determines the form Air temperature determines the form of precipitation that fallsof precipitation that falls

• 4 main types of Precipitation: Rain, 4 main types of Precipitation: Rain, Sleet, Snow and HailSleet, Snow and Hail

Types ofTypes of PrecipitationPrecipitation

RainRain SleetSleet

SnoSnoww

HailHail

HumidityHumidity• Humidity is the amount of water Humidity is the amount of water

vapor present in the airvapor present in the air

• Warmer air contains more water Warmer air contains more water vapor than cooler airvapor than cooler air

• Which has more water vapor?Which has more water vapor?

Humidity cont’dHumidity cont’d

• Relative humidity is the measure of the Relative humidity is the measure of the amount of water vapor present compared amount of water vapor present compared to the amount needed for saturationto the amount needed for saturation

• Dew point is the temperature at which Dew point is the temperature at which the air is saturated and condensation the air is saturated and condensation formsforms

• The closer the temperature is to the dew The closer the temperature is to the dew point, the more humidity there ispoint, the more humidity there is

Humidity Humidity MeasurementMeasurement•Humidity can Humidity can

be measured be measured with a tool with a tool called a called a psychrometepsychrometerr

Pressure and Air MassesPressure and Air Masses• An air mass is a large body of air that has An air mass is a large body of air that has

properties similar to where it developedproperties similar to where it developed

• For example, one that forms over land will be For example, one that forms over land will be dry. One that forms in the tropics will be warmdry. One that forms in the tropics will be warm

• As these air masses move, weather changes As these air masses move, weather changes occuroccur

• High pressure systems are usually fair and dryHigh pressure systems are usually fair and dry• Low pressure systems are usually cloudy and Low pressure systems are usually cloudy and

wetwet

Worldwide Air Mass MapWorldwide Air Mass Mapc=continental m=maritimec=continental m=maritimep=polar t=tropical p=polar t=tropical e=equatoriale=equatorial

IsobarsIsobars

Lines that connect areas of equal pressure

Sketch this picture

FrontsFronts• A front is a boundary between two air A front is a boundary between two air

masses of different density, moisture or masses of different density, moisture or temperaturetemperature

• Cold fronts occur when cold air moves Cold fronts occur when cold air moves towards warm air. They usually bring towards warm air. They usually bring thunderstormsthunderstorms

Front’s Cont’dFront’s Cont’d• Warm fronts form when warmer air moves Warm fronts form when warmer air moves

over colder air. These usually form hours over colder air. These usually form hours or days of wet weatheror days of wet weather

Fronts Cont’dFronts Cont’d

• Stationary fronts occur when the boundary Stationary fronts occur when the boundary between two fronts stops advancing. They between two fronts stops advancing. They may remain in place for several daysmay remain in place for several days