The measurements during the HEAT campaign can best be demonstrated by describing one of the flights. A summary of the aerosol measurements conducted on August 23, 2004 is given in here. Traverses upwind (to the south of the city) and downwind (on the north side of the city) were made at cloud base to document the aerosols being ingested by the clouds. This was followed by in-cloud measurements at progressively higher elevations to document the effect of the aerosols on the cloud properties. The subcloud measurements for this flight are provided in the figure.
 

The figure shows CCN data from the SOAR Cheyenne II during a flight downwind and upwind of Houston. Calculated backtrajectories are represented by the two yellow lines that terminate along the blue leg of the flight track. The line colors used in the top graph showing measured CCN concentration at 0.5% reflect the position along the flight track shown on the map. CCN concentrations immediately downwind of Houston were observed to be as much as 10 times higher than that measured on the east, west, and south sides of the urban plume. The cause of the bimodality in concentration is not known, although similar observations were made during the TexAQS study in 2000.

The HEAT project was funded by the National Science Foundation through the Texas A&M University (TAMU) Aerosol Research group.