In principle the detection of the atmospheric hole above our upper atmosphere is much like observing a fly walking across a television screen. Of course, Earth is much larger, as is the size of the atmospheric holes. The amount of cometary water vapor which is necessary to provide the atmospheric hole is in the range of 20 to 40 tons. The history of the impact of a small comet with this amount of water snow as it arrives from interplanetary space is shown in Figure 3 . The fragile comet is disrupted at altitudes of roughly 800 miles just above our atmosphere.
Sunlight is a very efficient energy source for converting the cometary snow into a water cloud.
The small comet approaches the Earth at speeds of approximately 35,000 miles per hour. The diameter of a small comet before disruption is typically tens of feet, typical of a small house, but the expansion of the water cloud after its release from the disrupted small comet is rapid. This rapid expansion provides a cometary water cloud of tens of miles in size, and the impact with the atmosphere is relatively benign. The water cloud is then slowed and mixed with the upper atmosphere. This is nothing greatly objectionable about the presence of small comets or about the above impact scenario.