Wind speeds

[SDB777]

As a novice in weather observation.....could someone explain why the winds are always so high at the summit of Mt. Washington? Been hiking all over these mountains and never encountered the winds on those that I did on the numerous times going to the Mt Washington.

Or was I just lucky enough to summit all the others during a lack of wind? I really don't believe that to be the answer due to the number of hikes and I'm just not that lucky of a person.


Thanks.......


Scott (got legs? give me a mountain to climb) B

[Bill O]

Most simply, mountain tops are windy places. They protrude into the atmosphere where a lack of friction leads to higher wind speeds. Also, winds hitting the lower slopes are forced upward over the summits and ridges. The result is an increase in wind speeds.

Now, why is Mount Washington windier than most mountains? I'll elaborate when I have more time this afternoon.

[Brad]

On an Observatory tour we were told that there is an upper ceiling to the atmosphere. The winds are forced up and over the mountains and must squeeze between the mountain and that ceiling. This causes the wind speed to go up at the summit an in a venturi effect.

How is this Bill?

[Bill O]

On an Observatory tour we were told that there is an upper ceiling to the atmosphere. The winds are forced up and over the mountains and must squeeze between the mountain and that ceiling. This causes the wind speed to go up at the summit an in a venturi effect.

How is this Bill?

That's right. The ceiling would be better described as a stable layer. Usually a temperature inversion above the summit. When winds hit the side of Mount Washington they are squeezed between the summit and the stable layer and forced to accelerate.

The topography of Mount Washington also aids in this acceleration. The smooth valleys/drainages act to concentrate the winds even more.

The White Mountains are significantly higher than any other mountains in the region. 2,000 feet taller than the Greens, and 1,000 feet above the Franconia Ridge. The strongest winds on Mount Washington currently come from the northwest. If you look at a map you'll notice that it is relatively flat in that direction.

The record wind came from the southeast off the coastal plain of Maine. A mostly flat area that gently slopes up to Mount Washington. It doesn't hurt that Mount Washington is only 75 miles from the ocean either.

A running joke is that Mount Washington is windy because of three storm tracks. This is not entirely accurate. Three major storm tracks do pass over Mount Washington, but they also pass over North Conway and many other locations which are not that windy. The presence of these storm tracks simply means there are many more opportunities for strong winds. Add this to all the contributing factors from above and viola, its very windy on Mount Washington.

[Brad]

I would also guess that if Mt Washington were just a peak without a long ridge the winds would just go around the summit. Because there is a long ridge of mountains the winds get forced up and over the ridge and peaks.

[SDB777]

Thanks for the explanations.

Knew that the air was squeezed between the land and the "thermal zone", but I was aways under the understanding that the upper layer would be much higher. Unless it fluctuates extremely in the atmosphere? Or more then likely I was just told wrong information(wouldn't be the first time).

It also never entered my mind that the land was "smoother" leading to the range that Mt. Washington sits in. After all, the drive there is almost as exciting as the hike(not really, but it sounds good).


Scott (weather = ulimate reality show) B

[Bill O]

Thanks for the explanations.

Knew that the air was squeezed between the land and the "thermal zone", but I was aways under the understanding that the upper layer would be much higher. Unless it fluctuates extremely in the atmosphere?

I think its a fair assessment that the stable layer fluctuates greatly. Sometimes its the tropopause at 35,000+ feet, while other times it might be at 8,000 feet.

An acoustic sounder would be a cool instrument on the summit to measure the temperature of the atmosphere a few thousand feet above the summit.