There are three main types of lenticular clouds: altocumulus standing lenticular (ACSL), stratocumulus standing lenticular (SCSL), and cirrocumulus standing lenticular (CCSL), varying in altitude above the ground. Although the clouds are over the mountains, these are NOT mountain wave clouds. g Intense waves can present a significant hazard to aviation by producing severe or even extreme clear air turbulence. Wave clouds form when air flows over a raised landform. Wave clouds typically form when a mountain, island, or even another mass of air forces an air mass to rise. ϕ Weather fronts mark the boundary or transition zone between two air masses and have an important impact up…, The classification of clouds into types was first proposed by Luke Howard in 1802 and we largely use the s…, Contrails are frequently seen criss-crossing the sky and are created from water vapour coming out of an ai…. In a way, Lenticular clouds warn pilots of the presence of mountain waves. They are periodic changes of atmospheric pressure, temperature and orthometric height in a current of air caused by vertical displacement, for example orographic lift when the wind blows over a mountain or mountain range. [1][2][3] b. are usually associated with prominent mountain ranges. Mountain Wave and Rotor Clouds over the Colorado Front Range. Skilled (and brave) glider pilots, on the other hand, like them, because they can tell from the shape of the clouds where the air will be rising. The most distinctive are the sharp-edged, lens-, or almond-shaped lenticular clouds, but a variety of stratocumulus , altocumulus , and cirrocumulus forms appear in both the main, vertically propagating waves and in the lee waves. This is because the presence of the mountain wave results in severe turbulence of the aircraft’s rotor systems. Thermal (Convective) Turbulence. [5] Usually a turbulent vortex, with its axis of rotation parallel to the mountain range, is generated around the first trough; this is called a rotor. ( N Roll clouds. is the vertical profile of potential temperature. The vertical motion forces periodic changes in speed and direction of the air within this air current. castellanus, billow, lenticular, rotor, banner, fractus, etc.) The vertical airflow component of a standing wave may exceed 8,000 ft/min. {\displaystyle N\cos {\phi }} Pilot have come to accept all these names for wave activity regardless of where the lenticular clouds are positioned. By Caitlin O'Kane June 19, 2019 / 8:31 AM / CBS News Seven weird weather phenomenons ... the clouds will whip up into wave … Lee waves occur when a wind of 25 knots (46 km/h) blows over a mountain. Both lee waves and the rotor may be indicated by specific wave cloud formations if there is sufficient moisture in the atmosphere, and sufficient vertical displacement to cool the air to the dew point. Pilots of powered aircraft tend to avoid flying near lenticular clouds because of the turbulence that accompany them. These clouds form in the crests of mountain waves (lee waves) if the air is relatively humid. The most common form is mountain waves, which are atmospheric internal gravity waves. Rising, descending or turbulent air in or above the lee waves can cause overspeed or stall, resulting in mach tuck and loss of control, especially when the aircraft is operated near the "coffin corner". These lens-shaped orographic wave clouds form when the air is stable and winds blow across hills and mountains from the same or similar direction at different heights through the troposphere. They did this for the first time on August 30, 2006 in Argentina, climbing to an altitude of 15,460 metres (50,720 ft). These air parcel oscillations occur in concert, parallel to the wave fronts (lines of constant phase). 5 years ago. d. are standing waves. If there's enough moisture in the air, and the air at the top of the crest of the wave reaches the dew point, a cloud will form. However, these waves can be present beyond the clouds, and may exist even when no clouds are formed. A fairly stable lenticular Lee waves provide a possibility for gliders to gain altitude or fly long distances when soaring. 22. (CNN) — A rare formation of clouds wowed onlookers at Virginia's Smith Mountain Lake on Tuesday. What are mountain wave clouds and how do they form? This is a "signpost of the sky" indicating that mountain wave activity is present. Energy is transmitted along the wave fronts (parallel to air parcel oscillations), which is the direction of the wave group velocity. Recognize special clouds (e.g. “At the wave crest, you get clouds. Otherwise, when these clouds cannot form in the absence of enough moisture in the air, the presence of a mountain wave is hard to identify, and this can be potentially dangerous to the airplane. The waves or clouds downwind from the mountain are the mountain are the "standing wave" or "lee wave." ϕ When the air hit the edge of the mountains and began to pass over, it began to oscillate—much like the suspension of a car bounces after it goes over a speed bump. The most distinctive are the sharp-edged, lens-, or almond-shaped lenticular clouds, but a variety of stratocumulus , altocumulus , and cirrocumulus forms appear in both the main, vertically propagating waves and in the lee waves. This KH cloud, to be specific the lenticular clouds because of the aircraft ’ s systems! Called the `` standing wave '' or `` lee wave. cloud is low... 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