Physics Photo of the Week
Animated
Cloud Wave
Notice
in the animation that the dark wave cloud is forming at the top of the
image. Air is rising and condensing as a cloud when it reaches
the specific height where the dew point is reached. The cloud
holds its shape as it propagates toward the Great Craggy
Mountains. It is believed that the clouds are dynamic -
undergoing convection at the same time as they are propagating down
wind. If so, these wave clouds are showing Kelvin-Helmholtz waves
due to different air layers travelling at different speeds - somewhat
like water waves caused by wind. Here the surface air is
relatively calm, while the clouds are moving away from the
camera. The dark parallel clouds are the bottom of the wave
crests that form either within the thick layer of clouds or above the
cloud layer.
The
picture at the right is
an example of a Kelvin-Helmholtz wave cloud. This wave cloud was
published by Mark Taylor on Earth
Science Picture of the Day on January 8, 2007. The sideways
views of the Kelvin-Helmholtz wave clouds are much more impressive, but
I have never seen any to animate. Any one with a digital camera
and tripod can make animated cloud pictures. If anybody can
photograph an animated sequence of the Kelvin-Helmholtz waves please
send them to me.
The animated image above was made by taking a photograph manually once every 10 sec. The 3 min 20 sec sequence was played back at 20 frames per sec. This speeds up the animation by a factor of 200 times. Open Office 2.0 has the tools to produce an animated "gif" image. Without the timelapse and rapid playback, it is very difficult to discern the motion of the clouds. Without producing an animated "gif" image, a slide viewer that permits rapid playback of sequential images shows the animation very well. Irfanview (by Irfan Skiljan - available free for personal use from irfanview.com) works very well for Windows.
Notice
in the animation that the dark wave cloud is forming at the top of the
image. Air is rising and condensing as a cloud when it reaches
the specific height where the dew point is reached. The cloud
holds its shape as it propagates toward the Great Craggy
Mountains. It is believed that the clouds are dynamic -
undergoing convection at the same time as they are propagating down
wind. If so, these wave clouds are showing Kelvin-Helmholtz waves
due to different air layers travelling at different speeds - somewhat
like water waves caused by wind. Here the surface air is
relatively calm, while the clouds are moving away from the
camera. The dark parallel clouds are the bottom of the wave
crests that form either within the thick layer of clouds or above the
cloud layer. The
picture at the right is
an example of a Kelvin-Helmholtz wave cloud. This wave cloud was
published by Mark Taylor on Earth
Science Picture of the Day on January 8, 2007. The sideways
views of the Kelvin-Helmholtz wave clouds are much more impressive, but
I have never seen any to animate. Any one with a digital camera
and tripod can make animated cloud pictures. If anybody can
photograph an animated sequence of the Kelvin-Helmholtz waves please
send them to me.The animated image above was made by taking a photograph manually once every 10 sec. The 3 min 20 sec sequence was played back at 20 frames per sec. This speeds up the animation by a factor of 200 times. Open Office 2.0 has the tools to produce an animated "gif" image. Without the timelapse and rapid playback, it is very difficult to discern the motion of the clouds. Without producing an animated "gif" image, a slide viewer that permits rapid playback of sequential images shows the animation very well. Irfanview (by Irfan Skiljan - available free for personal use from irfanview.com) works very well for Windows.
Physics Photo of the Week
is published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature an interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to dcollins@warren-wilson.edu.
Click here to see the Physics Photo of the Week Archive.
Click here to see the Physics Photo of the Week Archive.
Observers are invited to submit
digital photos to:
