Use the toggle buttons on the right to enable or disable display of the indicated data. Groups of mutually exclusive data are indicated by indentation and the presence of "radio button" style checkboxes. If a group has a parent checkbox, as with the Satellite Image group, you must select that parent checkbox in order to see any of the images in the group.
The infrared image and map boundaries get loaded when the applet first starts, while the other data gets loaded from the server the first time the associated button is selected. Selecting the Reload from Server button causes data to be reloaded from the server the next time it is displayed. The Applet Help button should get you to this document, if your browser supports loading other documents from within applets .
Satellite Images - These are images taken from the GOES-8 geosynchronous satellite:
Visible - An image taken in the range of the spectrum that corresponds to what the human eye sees. You should be able to distinguish clouds, water, and continental boundaries.
Water Vapor - An image taken in the range of the spectrum where moisture reflects light. Generally, the brightest areas contain the most moisture while darker areas are drier.
Surface Reports - These are actual recorded observations from weather stations.
The lines coming out of the cloud cover circles are wind barbs, which indicate wind speed and direction. The wind is coming from the direction the barb attached to the circle, e.g., a north wind is indicated by a barb attached to the top of the circle. The speed of the wind is indicated by the tail on the barb. Thicker tails and those with more segments indicate stronger winds. No barb indicate calm conditions, i.e., the wind has no direction or speed.
The numbers surrounding the cloud cover circle are temperature (upper left), dew point (lower left), and pressure (upper right).
Isotherms - lines of constant temperature. They allow you to see areas of high and low temperature, as well as the how fast temperature changes with respect to distance.
Isobars - lines of constant pressure. They allow you to see areas of high and low pressure, as well as the how fast pressure changes with respect to distance. They can help identify fronts and areas of strong winds.
Frontal Analysis - These are areas of changing weather, as well as high and low pressure centers.
Radar Summary - a composite of radar station images. It shows areas of active precipitation. Dark blue corresponds to light precipitation while red and yellow indicate heavy precip.
Map Boundaries - These indicates boundaries for countries, states, provinces, and large bodies of water.