|FTLComm - Tisdale - November 21, 2000|
across the Northern Grainbelt this morning we are enshrouded in fog. A truck who
had left Melfort for Humboldt then came to Tisdale reported that they visibility
was generally poor everywhere but the deceptively slipper highway surface was more
of a concern. He said that it was hard to distinguish the level of traction available.
Fog is produced when the temperature and the dew point ( point at which water condenses) become the same. When we look up and see a cloud that is the level where the water in the air turns visible. But there are other causes of fog. With
|temperatures near or at dew point more fog is produced or generated with fast moving
air. The picture at the top of this page and above illustrate this in a remarkable
way. Visibility around Tisdale at 9:30 was half a mile but at North Steel Industries
it was down to just under a car length. The source for the thick fog was the sand
blasting operation. The compressed air released in the sandblasting process expands
rapidly as it comes from the gun and as it does it absorbs a lot of heat from the
already chilled air this further lowers the temperature of the surrounding air and
the fog thickens proportionately.
Through out the area frost is building up on the trees and this example below is a typical example of this morning's hoar frost.