Heat flux at the air/ground interface was observed and analysed for va
rious pavement materials on summer days. The surface temperature, heat
storage and its subsequent emission to the atmosphere were significan
tly greater for asphalt than for concrete or bare soil. At the maximum
, asphalt pavement emitted an additional 150 W m(-2) in infrared radia
tion and 200 W m- 2 in sensible transport compared to a bare soil surf
ace. Analyses based on a parallel layers model of the atmosphere indic
ated that most of the infrared radiation from the ground was absorbed
within 200 in of the lower atmosphere, affecting air temperature near
the ground. With large difference between air and ground surface tempe
rature at noon, the rate of infrared absorption by the lower atmospher
e over asphalt pavement was greater by 60 W m(-2) than that over the s
oil surface or concrete pavement a figure comparable to the absorption
by turbulent transport.