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ISOBARS. Familiar idea, new focus !. Isolines ( review). An isoline is a line connecting points of equal value. Examples of isolines:. Contour: points of equal altitude Isotherms : points of equal temperature Isobar : points of equal barometric (air) pressure - PowerPoint PPT Presentation
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ISOBARSFamiliar idea, new focus !
Isolines
(review)
• An isoline is a line connecting points of equal value.
Examples of isolines:• Contour: – points of equal altitude
• Isotherms: – points of equal temperature
• Isobar:– points of equal barometric (air) pressure
• (The weather channel loves isolines!)
Rules for Drawing Isolines:
• 1. Isolines connect points of equal value.
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1510
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10
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• 2. Isolines are gentle, curving lines- no sharp corners.
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• 3. Isolines are always closed curves even though the map might only show part of it.
• 4. Isolines NEVER cross- this would mean that one point has two different values.
Ex: one spot has two temperatures?
20°
30 °
40 ° 50 ° 60 °
X
YZ
• 5. Isolines usually are parallel. (They have a parallel trend.)
Gradient• Gradient shows how quickly the value
changes from one point to another.
Gradientvalue
dis c e
tan
Our “VALUE” is air pressure, when talking about isoBARS
BARs BARometer air pressure
• A steep (high) gradient changes quickly and the isolines are close together.
• A gentle (low) gradient changes slowly and the lines are far apart.
Steep areaGentle area
HL
1016 mb
HL
1012 mb
1016 mb
HL
1008 mb
1012 mb
1016 mb
HL 996 mb
1008 mb
1012 mb
1016 mb
HL 996 mb
1008 mb
1012 mb
1016 mb
1000 mb
HL
1004 mb
1000 mb
996 mb
1008 mb
1012 mb
1016 mb
HL
1004 mb
1000 mb
996 mb
1008 mb
1012 mb
1016 mb
Follow up questions:
1. Describe the wind motion in the H.
2. Describe the wind motion in the L.3. In what area is the wind speeds the
greatest?
4.Winds go from ___ to ____ for pressure.
Summary
• Winds around a High blow in a clockwise direction away from the center. (“The clock is high.”) Highs usually have fair weather.
• Winds around a Low blow in a counter-clockwise and inward. (“The counter is low.”) Low pressure systems often have stormy or unsettled weather.