STRANGE WEATHER ON SNOWBALL EARTH

At night during the summer a thin haze of ice crystals would have formed near the ground, which would have been colder than the overlying atmosphere. Much of this haze would have dissipated when the ground and adjacent air warmed during the day, but some crystals could have been carried aloft by weak convection. There would have been no towering cumulus clouds and very little wind. There would have been little that we would recognize as precipitation. The atmosphere was too dry.

In winter, the ground would have been colder than the atmosphere both day and night. Midlatitude cyclones may have come and gone in the free atmosphere, but would have had little effect on the ground, isolated from the overlying atmosphere by the strong, stable, temperature inversion. There might have been thin clouds resembling cirrostratus in the upwelling regions of the cyclones, but again very little precipitation.

This strange weather is a consequence of the aridity of the atmosphere and the solidity of the ocean. The ice-covered ocean does not transport heat to high latitudes and it does not store large amounts of heat in the summer for release during the winter. The longwave opacity of the dry atmosphere is low, so radiative coupling between ground and atmosphere is weak. In addition, latent heat plays no significant role in the transport of energy either vertically or horizontally. Ground temperatures therefore depend mainly on insolation, little affected by or affecting the circulation of the atmosphere overhead.