Clouds Formation

Stratiform-category clouds generally form as the result of non-convective lift of relatively stable air, especially along slow moving warm fronts, around areas of low pressure, and sometimes along stable slow moving cold fronts. Precipitation is generally steady and widespread, with intensity varying from light to heavy according to the thickness of the stratiform layer as determined by moisture content of the air and the intensity of the weather system creating the clouds and weather. Low stratiform clouds can also form in precipitation below the main frontal cloud deck where the colder air is trapped under the warmer airmass being force above by the front. Non-frontal low stratiform cloud can form when advection fog is lifted above surface level during breezy conditions.
Cirriform-category clouds form mostly at high altitudes along the very leading edges of a frontal and/or low pressure weather disturbance and often along the fringes of its other borders. They are generally non-convective but occasionally acquire a tufted or turreted appearance caused by small scale high altitude convection. These high clouds do not produce precipitation as such but can merge and thicken into lower stratiform layers that do.
• Families and cross-classification into genera
The individual genus types result from the physical categories being cross-classified by height range family within the troposphere. These include family A (high), family B (middle), family C (low), family D1 (moderate vertical with low to middle bases), and family D2 (towering vertical with low to middle bases). The family designation for a particular genus is determined by the base height of the cloud and its vertical extent. The base height range for each family varies depending on the latitudinal geographical zone.