AOS 101 Discussion 303 TA Brian Miretzky

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AOS 101 Discussion 303TA- Brian Miretzky
Contouring February 3rd, 2008
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REVIEW

• Station models are an efficient and concise way
  to represent weather conditions at multiple
  locations
• How to analyze these station models
• Lets do some quick practice plotting

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Is there anything better

• Station models do a good job of telling us what
  the weather conditions are like over a large area
  or at one station at one time
• But contouring gives us even more information
• Contoured maps give easy to read general
  information about small to large areas
• Contoured maps help in easily diagnosing and
  depicting weather features and variables
• It helps your art skills!!!!!

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Contouring, Real Life
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Contouring
Contoured maps of certain variables (like this,
of temperatures at 850 mb) help to graphically
show locations of strong fronts, low/high
pressure systems, etc.
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How to think about contouring
Think of contouring as a topographic map, where
the lines represent places of constant height
above sea level. If you were to walk along one
of these lines, you would ALWAYS be at the same
height above sea level.
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What else can be contoured?

• Isopleth a line on a map connecting points at
  which a given variable has a specified constant
  value
• Isobar A line of constant pressure
• Isotherm A line of constant temperature
• Isodrosotherm A line of constant dewpoint
• Isotach A line of constant wind speed
• Isohyet A line of constant precipitation
  accumulation
• Isoneph A line of constant cloudiness
• Isohaline A line of constant salinity
  (saltiness in the ocean)
• Isoheight A line of constant height

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Isobar Line of constant pressure
http//www.spc.noaa.gov
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The winds are generally almost parallel to the
isobars. We call this geostrophy.
http//www.spc.noaa.gov
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Isotach Line of constant wind speed and
Isoheights Lines of constant height
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Isotherm Line of constant temperature
http//rap.ucar.edu/weather/surface
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Rules and Tips for Contouring

• Contours will never cross each other
• Contours never branch or fork, they are always
  one continuous line
• Do not create contours where there is no data
  (i.e., over the oceans)
• Always label your contours
• Contour at evenly spaced increments (for surface
  temperature, well do every 5 degrees Fahrenheit,
  and for sea level pressure, every 4 millibars)

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Rules and Tips for Contouring Cont.

• Use a pencil! You will be erasing
• Locate regions of high and low values first
• Initially, sketch out how you will be making
  your first few contours
• Make your lines as smooth as possible.
• Ignore outliers, data that doesnt seem like it
  fits with the big picture.
• If you need more help, try tutorial on web

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Examples

• Say these observations are temperatures. Where
  should we draw the 15o F isotherm??

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Examples

• Say these observations are temperatures. Where
  should we draw the 15o F isotherm??

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Examples
Say these observations are temperatures. Where
should we draw the 75oF and 80oF isotherms??
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Examples
Say these observations are temperatures. Where
should we draw the 75oF and 80oF isotherms??
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• Now for the hard part, lets try to contour
  ourselves...