JPATS Weather - NETC
JPATS Weather - NETC
JPATS Weather - NETC
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<strong>JPATS</strong> AVIATION WEATHER BOOKLET<br />
Figure 4-3 — Mountain Wave Turbulence<br />
Even though mountain wave turbulence may be present, when the airflow begins to move up the<br />
windward side of the mountain, is usually fairly smooth as the orographic lifting imparts the<br />
vertical component to the motion of the air. The wind speed gradually increases, reaching a<br />
maximum near the peak of the mountain. Past the peak, the air naturally flows down the leeward<br />
side, completing one cycle of oscillation and setting up the standing wave pattern of the<br />
mountain wave turbulence. Downwind, perhaps 5 to 10 miles from the peak, the airflow begins<br />
to ascend again, where the rotor or lenticular clouds may appear. Additional waves, generally<br />
less intense than the primary wave, may form farther downwind. Note in Figures 4-3 and 4-4 that<br />
the mountains are on the left and the wind is flowing from left to right.<br />
Figure 4-4 — Lenticular Clouds<br />
While clouds are usually present to warn aircrews of mountain wave activity, it is possible for<br />
wave action to take place when the air is too dry to form clouds, producing CAT. Still, cloud<br />
Version 3.2/Dec 08 4-5
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