Pressure and Wind on the Summit

2015-01-17 17:51:46.000 – Michael Dorfman, Weather Observer/IT Specialist

The summit of Mount Washington receives some of the highest wind speeds in the world. Our record high gust of 231 miles per hour, recorded in April of 1934, was a world record wind speed measured on the surface of the Earth. While this was broken in 1996 by a hurricane off the coast of Australia, we still hold onto the fact that we have recorded the fastest wind speed observed by man (the Australian station was automated). So, what gives us our strong winds? It’s all about the pressure.

When you open a shaken-up soda bottle, the high pressure gas in the bottle quickly shoots out into the low pressure environment outside the bottle. Our atmosphere acts in a similar way. Our atmosphere is full of different areas of high pressure and low pressure, thanks to the unequal heating between the poles and the equator. Air in high pressure regions tends to travel towards air in low pressure regions.

To demonstrate this idea in a more visual form, below is a graph of pressure change on the summit vs wind speed. This an average, based on a small selection of 27,000 data points from our records between 2007 and the present. It is evident that wind speed and pressure change are directly correlated; when pressure changed more quickly, wind speed is generally faster.

 

You can see the pressure changing on the summit. As the summit cleared from fog last night (indicating increasing pressure), wind speeds ramped up as high pressure pushed in behind the low pressure system that was in place. Once high pressure was firmly overhead today, the pressure gradient was not very tight, allowing for winds to slacken. As a low pressure system pushes in overnight, wind speeds will once again increase.

If you would like more information on wind speeds on the summit, please visit our Higher Summits Outlook, and if you want to experience these incredible winds first-hand, check out the various ways to get to the summit, including Observatory Day Trips, Overnight Trips, or hiking trips guided by the Observatory’s partners.

Michael Dorfman, Weather Observer/IT Specialist