Radiosonde temperature data from 147 stations in the Northern Hemisphere for the period 1964--85 have been used to investigate recent temperature trends in the troposphere and lower stratosphere. Experiments with atmospheric general circulation models indicate that increased concentrations of greenhouse gases in the atmosphere will lead to reduced temperatures in the stratosphere as well as increased temperatures in the troposphere. An index designed to identify this signal has been computed from the station data. This index has positive trend at most of the stations, consistent with the greenhouse effect. Over the hemisphere, the signal is statistically significant. However, opposing temperature variations in the troposphere and stratosphere are associated with many other forcing mechanisms and the results cannot be used to identify a specific mechanism. ¿ American Geophysical Union 1989