Inflatable passive falling spheres launched in conjunction with the DROPPS/MIDAS campaign during July 1999 are used to infer thermal advection and its relationship to Polar Mesospheric Summer Echoes (PMSE) and Noctilucent Cloud (NLC) events. Hodograph analysis, although not new, is used at mesospheric altitudes where non-hydrostatic conditions may possibly inhibit useful results. Nonetheless, the concept of applying thermal advection to PMSE and NLC events is tried here with a possibility of interpreting neutral atmosphere measurements and their relationship with the electrodynamic environment. Although the material presented represents only results from the DROPPS/MIDAS campaign, it shows changes in the temperature structure within a few hours at the time of the PMSE event that indicate thermal advection may be connected to temperature changes of a few degrees. The warm advection between 80 and 86 km may be significantly related to the height of the PMSE, i.e., 85 km. ¿ 2001 American Geophysical Union