What we call it when the temperature in a section of the atmosphere is decreasing so quickly that any air parcel that rises will find itself warmer, lighter and more buoyant than its surrounds. The further it rises the bigger the difference and so it will keep on going until it hits a layer of stable air above. During summer the lower half of the a [..]

The air stuck to the Earth by gravity.

Mountainwatch

A

The surface at which the atmospheric pressure is 500 hPa at every point. By plotting the height of this surface on a map we get a picture of the weather features at an altitude of about 5500 m and up in the atmosphere. These features are important because the drive the vertical motion that creates surface weather. They also help to steer the direct [..]

A depth of 5400 m between the 1000 hPa and the 500 hPa pressure levels in the atmosphere. The thickness of this 1000-500 hPa layer is largely dependent upon the average temperature in the layer and to a lesser extent on the moisture content. During a cold outbreak, the air is very dense and so this layer is thinner. When the thickness is less than [..]

The loss of snow by melting and evaporation. Ablation sucks.

What we call it when a section of the atmosphere is so stable (warm light air over cold dense air) that a parcel of air rising through it will always wind up cooler and heavier than its surroundings and want to sink again, even if condensation is occurring and releasing heat.

What happens when a drop of super-cooled liquid water collides with an ice particle and freezes on impact.

A fancy term to describe changes in the temperature of air due to expansion or compression. Air sinks, it is compressed and warmed adiabatically, without any exchange of heat with the outside environment (although there's always some mixing around the edges). Air rises, it expands and cools.