Day 47 Investigation 9 part 2 Air Masses and Weather Maps

Arrows and Scale Visualization Exercise 9.1

Resources P. 85

Color and Real vs Diagram Visualization Exercise 9.2

Resources, P. 89

Review Air Masses Air masses: – Large thick bodies of air – Uniform in temperature and humidity –Have distinct boundaries –Cover large areas of earth’s surface –Reach top of the troposphere –Names for the source region

Colliding Air Masses Air masses don’t stay in one place Warm air masses from the tropics move north and east Cold air masses from the polar regions move south and east

Colliding Air Masses Air masses don’t stay in one place Movement of air masses creates opportunity for air masses of different temperatures and humidity to collide

Meeting of Air Masses Remember the density bottles What is going on inside of the bottle? –Denser liquid below the less-dense one

Meeting of Air Masses Imagine –I reach north –Grab a cP (continental polar) air mass –Shrink it –Jam it into the bottle cP

Meeting of Air Masses Imagine –I reach south –Grab a mT (maritime tropical) air mass –Shrink it –Jam it into the bottle with the cP one What happens to the air masses? –Polar air sinks because it is denser –Tropical Air lifts to the top because it is less dense mT cP

Air Mass Model Gases and liquids have fluid movement The liquid in the bottle represents what would happen in real life with air masses

Fronts If air masses meet, a boundary forms Front –A boundary between two air masses

Origin of “Fronts” Originated after World War 1 Norwegian meteorologists The zone where 2 opposing armies clash is called a battlefront The boundary - violent weather changes often occur

Naming Fronts Takes the name of the air mass that is moving faster and overtakes a slower air mass

Cold Fronts A boundary that forms when a cold air mass overtakes warm air mass Clouds form Cold, dense air plows under warm, less dense air Warm, humid air rises and cools

Weather and Cold Fronts Effects from cold fronts happen quickly –Clouds form, can grow into thunderstorms –Rain or snow can fall Lightening and hail –Drop in temperature –Pressure increases Cold front symbol on weather map A cold front moves in

Warm Front The boundary that forms when a warm air mass overtakes a cold air mass Warm air slides up over cold air at a gentle slope Can be hundreds of km long

Weather and Warm Front Effects happen over long period of time –Air pressure decreases –Temperature rises at the surface –Clouds thicken and lower (first wispy, cirrus clouds) then others (cumulostratus, altostratus, nimobostratus, stratus, possibly fog) –Rain, snow, sleet or freezing rain begin to fall Warm front symbol on weather map A warm front moves in

Surface Observations Meteorologists receive weather observations from stations all over the United States and the world These are called surface observations

Surface Observations Surface Observations include: –Temperature –Humidity –Air Pressure –Wind Speed and Direction –Cloud Cover and Type –Precipitation Type and Amount

Look at Weather Symbols Use special codes or symbols to represent weather data on a map Typical weather symbol

Weather Symbol Short barb = 5 knots Long barb = 10 knots From which it is blowing

Surface Observations Programmed into a computer that plots the information on a map Used by meteorologist to make weather predictions

Practice Reading Weather Maps Open to page 57 of your lab book and see if you can read a weather map.