|
|
|
|
Noctilucent Clouds
11/26/2002
Listen in RealAudio 
Hi, I'm Bryan Yeaton and this is The Weather Notebook's weekly segment on Global Climate
Change.
Climate scientists are now studying "glow in the dark" clouds that appear high in the earth's
atmosphere in polar regions. These clouds are now being seen in lower latitudes which
researchers suspect may be related to climate changes. Jeff Rice of Boise, Idaho
reports.
Noctilucent clouds or clouds that shine at night are well-known in the polar regions. They
are made up of ice crystals and are so high in the upper atmosphere they still catch the rays
of the sun even after the sun has set. Physicist, Mike Taylor...
MT: They are very beautiful. They have an opally white or a pearl color and they basically
shine in the sky.
Several years ago Noctilucent clouds began showing up much further south than normal. Even as
far south as Logan, Utah. Taylor and his colleagues at Utah State University theorize that
this might tell us something about global warming.
MT: If we see clouds at lower latitudes or if we see them more often than before then we are
drawn to the conclusion that the conditions in the upper atmosphere have changed.
Here's the theory. As air in the lower atmosphere heats up because of the greenhouse effect
it rises just like a hot air balloon. As it rises it cools. This upcurrent of cooling air
makes it easier for clouds of ice crystals to form in the higher regions.
MT: You need very, very cold temperatures and that's especially the upper atmosphere, the
coldest place on Earth. In centigrade it could be from 120 degrees minus Centigrade or 140
degrees minus Centigrade there.
Scientists at Utah State have teamed up with NASA to develop a new satellite that will monitor
these ice clouds and the conditions that form them. They hope that one day it will lead to an
accurate barometer for global climate change.
The Weather Notebook is a production of the Mount Washington Observatory. Our global climate
change series is supported by the New England Science Center Collaborative and the Roy A. Hunt
Foundation.
|
|
