The increase in range at which mass fires could occur from an airburst of the type described in figure 6, but on a clear but cloudy day, is shown above. Since the postulated detonation would occur below the cloud cover, much of the upward directed light from the fireball gets reflected back to earth by the cloud cover. This results in fire ignitions at greater ranges from the ground zero point.

A further increase in the range at which mass fires might be ignited is shown for the circumstance in which both cloud cover and snow cover are present. In this circumstance, much of the heat from the fireball is not absorbed by the ground, but is reflected back toward the sky and to surrounding objects. The heat refected into the sky gets re-reflected back to earth by the cloud cover, resulting in fire ignitions at still greater ranges from the detonation point.

Since most of the Soviet Union has extensive cloud and snow cover during long periods of winter months, this could be a source of a "nuclear winter" assymmetry of the type mentioned on page 6 of the written testimony.

The region subject to both a blast wave of about 5 pounds per square inch and 10 calories per square centimeter thermal radiation is shown for a 2 kiloton air burst. The area subject to an immediate fire and blast hazard would be about one square mile. Also worthy of note is that early fallout of the type described in figures 2 through 5 would not be present.

If a one kiloton earth penetrating warhead is used instead, the 5 pound per square inch blast range would be reduced by about a factor of two and the thermal ignition effects from the fireball would be reduced to several hundred feet. However, fires would be highly likely out to at least the 5 pound per square inch point because of ignitions induced by the passage of the shock wave.

The debris cloud from the one kiloton earth penetrator weapon would only rise to about 10,000 feet. It would therefore not inject debris into the stratosphere, but would, of course, leave these materials in the troposphere.

Since the penetrator detonates underground, the radioactive bomb materials condense onto particles which are large relative to those carried aloft by the near surface burst discussed in figures 2 through 5. These large particles fall from the debris cloud rapidly, mostly being deposited near the target area and immediately downwind. While they represent a very serious threat to those in the target area, they do not represent a significant threat to a distant

attacker.

The approximate downwind area that could be subject to severe fallout from a one kiloton earth penetrator attack is shown above. This fallout, while very intense, would mostly be confined to an area within 5 to 10 miles downwind of the target. See figures 2 throuh 5 and 9 and 10 for an explanation of the fallout phenomenon.