Stratus cloud a region. Some call these clouds "high fog" for the fog-like cloud. While light rain may fall, this cloud does not indicate much meteorological activity. Stratus clouds form when a sheet of warm, moist air lifts off the ground and depressurizes, following the lapse rate. This causes the relative humidity to increase due to the adiabatic cooling. Stratus clouds look like featureless gray to white sheets of cloud. They can be composed of water droplets, supercooled water droplets, or ice crystals depending upon the ambient temperature. Stratus nebulosus clouds appear as a featureless or nebulous veil or layer of stratus
Mushroom cloud Layering of humidity in the atmosphere, responsible for the appearance of the condensation rings as opposed to a spherical cloud, also influences the shape of the condensation artifacts along the stem of the mushroom cloud, as the updraft causes laminar flow. The same effect above the top of the cloud, where the expansion of the rising cloud pushes a layer of warm, humid, low-altitude air upwards into cold, high-altitude air, first causes the condensation of water vapour out of the air and then causes the resulting droplets to freeze, forming "ice caps" (or "icecaps"), similar in both appearance and mechanism