In a low yield surface burst, of the type possible in a terrorist attack, the amount of thermal energy reaching a target at a specific distance may be half to three fourths of that from an air burst of the same total energy yield.

Thermal energy received at a distance will be affected by:

• Shielding due to buildings and terrain irregularities
• Absorption in low layer dust and water vapor
• Absorption by the heavier air near the earth's surface