[Picture Source: Compliments of Mr Ong Jek Yaw, 2010]
In the teaching of waves and standing waves, we often use the ripple tank to illustrate phenomenon associated with waves. Today, I learnt something from a very experienced colleague of mine (Mr Ong Jek Yaw). In reality, we have an extra large "ripple tank" in our sky! The rows and rows of clouds that form the sky are in reality known as wave clouds, and they are formed when the atmosphere is disturbed and a "gravity" wave travels through.
From what I understand, wave clouds are form when a thin and stable layer atmosphere is disturbed, e.g. when it passes over a mountain. The air disturbance can propagate like ripples in the pond when the stone hits the water. As the wave moves through the air, it undergoes repeated uplift and descent. If there is enough moisture in the atmosphere, clouds will form at the crests of these waves. In the descending part of the wave this cloud will evaporate due to adiabatic heating, leading to the characteristic repeating cloud/clear bands. (wikipedia)
Stationary waves form in the atmosphere can also result in structures observed as well.
Two particularly interesting wave clouds video can be found on youtube and are embedded below:
[ Video above from Youtube, by akrherz at http://www.youtube.com/watch?v=yXnkzeCU3bE]
[Video above from Youtube by RobyF5 at http://www.youtube.com/watch?v=Dvl3PrXwBkI&feature=player_embedded]
More about wave clouds can be found in the links below.
http://www.weatherquestions.com/What_causes_wave_clouds.htm
http://www.theweatherprediction.com/habyhints/64/
http://en.wikipedia.org/wiki/Wave_cloud
http://weathervortex.com/sky-ribbons.htm
No comments:
Post a Comment