GOES Image or
A GOES image provides the context for the detailed polar-orbiter image. The wide field
of view of the GOES image provides information on the current position of active
cyclones and a rough idea of the long wave trough and ridge pattern. A loop of GOES
images shows the recent development and movement of large scale features. Wave
patterns are much easier to identify in time lapse loops than from an image or group of
images. GOES loops can be taped from television weather broadcasts and shown in
the classroom.
Source of GOES Images
Downloading GOES images from the Internet or other source, and animating the
images in the classroom may prove to be overly cumbersome. The simplest method for
displaying GOES loops is television videotapes. A compact and comprehensive weather
discussion, complete with GOES loops, is provided each morning by “AM Weather” on
PBS. Other sources are local weather broadcasts as well as “The Weather Channel.”
Upper Air Information
The identification of wave patterns as well as jet stream and jet streak position is best
done using standard meteorological upper air charts. These are available from several
sources using the Internet. Many television broadcasts show the position of the jet
stream which, in most cases, is parallel to the upper air flow pattern. The location of jet
streaks is not a standard broadcast item and can only be obtained via upper air charts.
Upper Air Charts
Upper air charts are available on the Internet at the same location as satellite images.
They are usually identified by filename “uwxxyyzz.gif” [w is the level identifier, xx is the
month, yy is the day of the month, and zz is the time—Greenwich Mean Time). Upper
air charts are given for several levels in the atmosphere: 850 millibars (mb), 700 mil-
libars, 500 millibars, 300 millibars. A chart for conditions at 850mb at 1200 GMT, on
June 14 would have the file name 061412.gif. All upper air charts are plotted on a
constant pressure surface. For example, the 850 mb chart is created from observations
made as a radiosonde reaches a pressure of 850 mb. The altitude at this point varies
from place to place. Near low pressure centers, the altitude corresponding to 850 mb
will be much lower than the altitude corresponding to 850 mb near high pressure.
Therefore, low pressure areas are depicted on upper air charts as areas of lower height.
This can be a source of confusion. The jet stream is usually found around 300 mb or
200 mb. The location of short wave disturbances is best seen at the 500 mb level.
Temperature gradient information is best seen at 850 mb.
Surface Information
Surface data provides an idea of low-level temperature gradients, fronts, and the loca-
tion of low pressure centers. These are often available in the local newspaper as well as
on the Internet and TV broadcasts.