The US Air Force conducted studies to test the accuracy of the Appleman chart. Military pilots sometimes remark in their flight reports whether or not contrails form during their flights. Using these reports and observations of temperature, pressure and relative humidity, the USAF found that the forecasts using the Appleman method were correct about 60 to 80 percent of the time. Looking more closely at the data, they found that when no contrails were forecast, the forecast was correct 98 percent of the time! However, when contrails were forecast to occur, THE FORECAST WAS CORRECT ONLY 25 TO 35 PERCENT OF THE TIME, AND OFTEN FAILED TO PREDICT THE OCCURRENCE OF CONTRAILS. Thus, the Appleman chart tends to underpredict the occurrence of contrails and to overpredict the non-occurrence of contrails. For this reason, the USAF is actively investigating better ways to compute contrail formation. science-edu.larc.nasa.gov/contrail-edu/resources-activities-appleman_student.php
Posted on: Sat, 06 Jul 2013 01:17:23 +0000
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