the 500mb chart and shortwave vs. longwave troughs
TRANSCRIPT
The 500mb Chart and Shortwave vs.
Longwave Troughs
Information on the Chart• Isoheights
o Lines of constant heighto Dark solid lineso Analogous to lines on a topographic
map
• Isothermso Lines of constant temperature o Dashed red lines
• Wind speed and directiono Blue barbs and flags
• Dew Pointo Green numbers
Wind symbol convention
Information on the Chart
Isoheights
Isotherms
Wind information
Dew point
Uses• Starting point for making a forecast
o See general patterns in the atmosphere
• Identify troughs and ridges
• Trougho Area of lower heightso As you go into the trough, heights decreaseo Analogous to a valley on a topographic map
• Ridgeo Area of higher heightso As you go into the ridge, heights increaseo Analogous to a mountain on a topographic map
Troughs and Ridges
Ridge
Trough
Trough
Note height labels to determine if heights are increasing or decreasing
Shortwave Trough vs. Longwave Trough
• Longwave trougho Trough that has long wavelengtho Only about 3-7 in the entire Northern Hemisphere at any given
timeo Move slowly
• Shortwave trougho Trough that has short wavelengtho Many exist at any given timeo Move quicklyo Can be stand alone, or embedded within longwave troughs or
ridges• If embedded, look for little “kinks” in the isoheights
Examples
Longwave trough stretching over much of the U.S.
Longwave troughs
Shortwave trough over Ohio and Tennessee Valley, another entering southern California (and there are more)
Longwave trough
Shortwave trough
Longwave trough
SWT
SWT
SWT
SWT Shortwa
ve ridge
SWT = shortwave trough
Where are the shortwave and longwave
troughs?