Jul 10, 2007 4:55 pm US/Eastern
WeatherWise: How Dense Fog Forms
by Mish Michaels
BOSTON (WBZ) ―
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The Massachusetts collided with the Laura on Tuesday, July 10.
WBZ
Coast Guard investigators are trying to determine the cause of the commuter ferry boat collision in Boston Harbor, but it looks like dense fog could be to blame.
Fog is nothing more than a cloud that has formed on the ground. But when the fog gets thick, visibility can drop to zero make travel on foot, on a bike, in a car, and on boat very dangerous.
"All of a sudden I looked up and it looked like the whole bow of the boat was coming right in. It just smashed right in..it was so foggy you couldn't see," said ferry passenger Paula Marcangelo.
According to hourly weather observations, visibility over Boston Harbor dropped to zero around 6 a.m. and just over an hour later, the commuter collsion occured.
"The visibility was terrible today. We don't know if it was the cause of the incident. It is something we going to be looking to," said Zach Zubricki of the U.S. Coast Guard.
A tea kettle provides a good example of how fog forms. Water vapor from the kettle cools at room temperature and condenses into little droplets forming a fog-like cloud.
Last night this happened on a grand scale. Warm, humid air around 70 degrees cooled over the chilly waters (61 degrees) of the Atlantic.
As the air in contact with the water cooled, the water vapor condensed into tiny droplets forming a thick bank of fog.
On a visible satellite image, fog looks like a uniform white sheet. But if you're in it, you can't see anything.
Sunshine can cause the fog to lift or burn off simply by warming the air, resulting in improved visibility during the day.
All the ingredients are in place for fog formation again tonight. In fact, fog is forecast to form after midnight over coastal waters with visibility dropping to less than a mile.
This story is done through our partnership with the Museum of Science, Boston called Weatherwise. If you would like to learn more, visit us online at
www.mos.org.
(© MMVII, CBS Broadcasting Inc. All Rights Reserved.)
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