Interesting Video : Newton's Dark Secrets

 

Newton's Laws of Motion together with the study of dynamics forms the foundations of classical physics.  The A-level syllabus and hence the school dedicate alot of the time, especially in the first year in teaching of Mechanics.  My students are always facinated with Newton, his discovery of the three laws and then the Law of Gravitation.  They had also earlier, in their secondary school studied on Optics, where they read about Newton splitting the light into its various colours.  Usually students who do Physics will also do Math and also encounter Newton - Rhapson Method in the approximation of roots.

This "Father of Classical Physics" has therefore also astounded my students with his discoveries.  Sometimes I like to add a little twist to my lessons and therefore, if I have the time, I always like to show this video to my students as it forms a nice ending to especially the study of Mechanics.  My students are always surprised to find that Newton was afterall very human and had weird habits (having an obsession of alchemy and also trying to calculate the end of the world).  Though this video does not show the best side of Newton, it shows his passion and thirst for knowledge had also interest my students to find out more about other Physicists.

Waves in the Sky - Wave Clouds

[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