Weather PatternsLab 6-5

Pages 241 - 252

Weather Patterns

• AIM

• Understand how the variables we have learned about so far work together to create weather systems.

• OBJECTIVE

• Construct field maps and learn to identify patterns than can be used to predict weather.

Vocab• Synoptic Weather Map: A map that represents

all the atmospheric variables in an area.

• Isotherm: Lines on a map connecting points of equal temperature; generally run parallel with the equator as temperatures decrease with increasing distance from the equator.

• Barometric Pressure: The weight of the air in the atmosphere– High Pressure; nice weather– Low Pressure; bad/rainy weather

• Isobar: Lines on a map connecting points of equal barometric pressure.

• Convergence: Wind blowing toward the center (cyclone)

• Divergence: Wind blowing away from the center (anticyclone)

• Cyclone: Low pressure system with air moving inward toward the center.

• Anticyclone: High pressure system with air moving away and outward from the center.

• Air Mass: A large body of air with similar pressure, temperature and moisture. Acquired from a source region.

• Source Region: An area of Earth’s surface over which an air mass forms and acquires its characteristics.

• Front: The boundary between two air masses of different characteristics.

Calculating Gradient• Gradient is the rate of

change between two points and is calculated by dividing the difference between two points by the distance.

• For example: If Galveston, TX and Kansas City, KS are 700 miles apart and the temperature in Galveston is 60º and the temperature in Kansas City is 50º then . . .

• 60º - 50º = 10º (That’s your difference)

• Distance = 700 miles

• 10º/700 = .014º/Mile

• Gradient = .014º/Mile

• Are you ready to draw your Synoptic Weather Map?

Map A: Isotherms

• Connect points of equal value

• Use an interval of 10°F

• Stop your lines when they go off the coast.

If more dots are needed, add some…

Map B: Isobars• Write the following in an empty space on the map:

Millibars Station Model Code

1024.0 240

1020.0 200

1016.0 160

1012.0 120

1008.0 080

1004.0 040

1000.0 000

• Draw isobars

• Use an interval of 4mb.

• Label the highest pressure with an

• Label the lowest pressure with an

Map B: Isobars- Continued

Drawing isobars . . .

Map C: Wind PatternsDraw arrows…

Map C: Wind PatternsNow Draw Large Arrows…

Map D:Precipitation Patterns

• Draw a line encompassing the entire area where rain is falling.

• Lightly shade it in with pencil.

• Label the Air Masses.

Handy Dandy Earth Science Reference Tables, pg 13

• An Air Mass is a large region of air that has the same temperature and humidity.

• It gets its properties from hanging out in the same region for a while.

For example:

• If the source region is the gulf of Mexico and the air comes to Long Island…

• It will feel warm and moist to us: maritime tropical (mT).

• If it comes from central Canada…

• It will feel cold and dry to us: continental polar (cP)

What type of air mass?

Cool & moist: mP

mP

Cool & Dry:

cP

Warm & Moist:

mT

cT

mT

mP

mT

Make the Synoptic Map

• Use Instruction #1 as a check list of things to put on the map.

• Add the fronts.