MET 101 - Skew-T Diagram

Skew-T Diagram

As you are aware from reading the lab all of the data used in a Skew-T Diagram analysis comes from a radiosonde. These devices are launched twice a day from many sites in North America. The following MAP shows the locations of launch sites across North America and the Pacific Ocean. However, data is not only collected in the United States but all over the world. The following WORLD MAP shows the Global Climate Observing System Upper Air Network (GUAN). These are locations from which the upper atmosphere is monitored by the World Meteorological Organization. One of the main reasons why forecast models produce inaccurate results leading to inaccurate daily weather forecasts is because of the sparse network of upper-air observations. Ideally meteorologists would like to launch radiosondes from every city and large town in and around the United States every 3 hours. This is not feasible however do to the associated costs of an individual radiosonde launch which average between $256.00 and 281.00 per launch (depending upon the annual salary of the individual in charge of that particular launch). With this in mind meteorologists have turned to another source of upper-air data measured by commercial aircraft (AMDAR DATA - Automated Weather Reports from Commercial Aircraft) as they fly various scheduled routes across the country. These planes obviously must ascend and descend each flight and as they do so they measure temperature, wind speed, wind direction, latitude, longitude, altitude and time. In the United States there are six participating airlines. These are American, Delta, Federal Express, Southwest, United and United Parcel Service.

On your upcoming lab final you will need to be able to analyze one upper air sounding data set by following the directions as printed in the skew-t diagram lab. You do not have to waste your time memorizing the directions, just simply be prepared to follow the directions. The one thing that you do need to know is the layout of a skew-t diagram chart. In other words know where the 5 lines are, which directions they run, where the values of individual lines are listed etc.... This way when you follow the instructions you will understand for example when the directions tell you to draw a line parallel to the isotherms. To see present and past sounding data and skew-t images for cities in the United States and around the world CLICK HERE. At this site you can choose to view past or present upper air data in text format or you can view a gif image of the skew-t diagram plot.