John Wheeler, WDAY, Published October 05 2012
Weather Talk: Tunnel under interstate fascinating on windy daysLast Tuesday, the wind was strong from the south when I was running in south Fargo.
North of Lincoln Elementary School, there is a sidewalk that passes through a tunnel under Interstate 94. This tunnel is fascinating on windy days. When the wind is strong from the north or south, there is always an opposite wind inside the tunnel.
This is an architectural demonstration of Bernoulli’s Principle, which is basic calculus derived from Newton’s Second Law of Motion. As the wind first develops, air flowing up and over the freeway pulls a small amount of air from the windward entrance of the tunnel. As the air then flows down the other side of the freeway, a small amount of air is pulled back into the tunnel to make up for the lost air at the other end. As the wind increases, the opposing wind in the tunnel increases.
The effect is most noticeable when I am running with the wind and then feel wind in my face inside the tunnel.
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