Cloud formation and properties
Clouds form in areas where moist air cools, generally by rising. This can happen
* along warm and cold fronts,
The actual form of cloud created depends on the strength of the uplift and on air stability. In unstable conditions convection dominates, creating vertically developed clouds. Stable air produces horizontally homogeneous clouds. Frontal uplift creates various cloud forms depending on the composition of the front (ana-type or kata-type warm or cold front). Orographic uplift also creates variable cloud forms depending on air stability, although cap cloud and wave clouds are specific to orographic clouds.
Cloud properties (mostly, their albedo and rain-out rate) are strongly dependent on the size of the cloud droplets and the manner in which these particles coalesce. This is in turn affected by the number of cloud condensation nuclei present in the air. Because of this dependence, and lack of global climatological observations, clouds are difficult to parametrise in climate models and a bone of contention within the global warming debate. Condensation of steam in liquid water or ice happen initially around some kinds of micro-particles of solid matter called hub of condensation or freezing. At this stage the particles are still very small and collisions and aggregation can’t be the principal factors of growth. What happens is called the “Bergeron principle”. This mechanism stands on the partial pression of ice saturation being lower than liquid water. Which means that in a midst where coexist ice crystals and droplets of water supercool.