Atomic dust clouds may have caused the recurrent ice ages in the past, Donald H. Menzel, Professor of Astrophysics, reported Saturday to the American Association for the Advancement of Sciences.

By now, he claimed, most astro-physicists agree that the recurrent seasons of hot and cold periods have been somehow connected with the sun.

The past four ice ages in a million years have not been accounted for by anything happening on the earth. Furthermore the varying output of heat from the sun could not have caused the great terrestrial temperature changes.

However, one thing is certain according to Mensel. The whole solar system is made up of enormous clouds of tiny dust particles. These are so minute that earthly observers would never notice them, and the world would still receive the same amount of solar energy.

Yet long-range radiation rays, says Menzel, which usually fly off from the earth, would be stopped by the cloud and retained. Thus the weather would be come warmer, the proper weather for an ice age. More water would evaporate from the earth and fall at the poles as snow, compress itself into ice and start moving as a glacier.

But, claims Menzel, the weather would have to be just right. If it became too cold, then too little snow would fall to form ice. On the other hand, a spell of unusually warm weather would melt the ice packs.

Professor Menzel continues to point out that the hypothetical dust cloud which enveloped the earth was thicker at some places than at others. When the world passed through a thick mass of dust, the earth experienced fairly warm weather and the tropics probably flourished. Then as the planet passed into thinner areas, the earth would grow cold and led packs formed.

Probably, in times of great warmth even the Antartic and Arctic region flourished with vegetation.