JPATS Weather - NETC
JPATS Weather - NETC
JPATS Weather - NETC
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<strong>JPATS</strong> AVIATION WEATHER BOOKLET<br />
Methods of Lifting<br />
The four methods of lifting are convergence, frontal, orographic, and thermal (Figure 2-20).<br />
Convergence of two air masses, or parts of a single air mass, force the air upward because it has<br />
no where else to go. Because of the shape of cold fronts, as they move through an area, they will<br />
lift the air ahead of the cold air mass. Orographic lifting is a term indicating that the force of the<br />
wind against a mountainside pushes the air upward. Thermal lifting, also known as convective<br />
lifting, is caused when cool air is over a warm surface, and it is heightened by intense solar<br />
heating.<br />
Figure 2-20 — The Four Lifting Methods<br />
Stability and Flight Conditions<br />
Cloud types are helpful in identifying conditions of stability or instability. Cumuliform clouds<br />
develop with unstable conditions and stratiform clouds develop with stable conditions (Figure 2-<br />
21), assuming sufficient moisture exists for cloud development.<br />
Figure 2-21 — Clouds in Stable and Unstable Air<br />
Version 3.2/Dec 08 2-19