The Big Wind, Part 3: The Measurement

Ok, so back to the discussion about The Big Wind. Today is the third part of the series and will take a look at that actual measurement of the wind in two ways. First of all, the location on the summit where the wind was measured and secondly the instrument that was used to make the measurement.

First up is the location on the summit the wind was measured. In 1934, the Observatory was not located in the same building we are now. From the founding of the organization in 1932 until 1937, we were located in the Mount Washington Auto Road Stage Office, shown here:

The building that you see in this picture is actually a replica of the original building, but it stands on the exact same spot as the original. This is a wood frame building that is literally chained down to the mountain. Here is a picture of those chains:

The Stage Office is located on the southeast quadrant of the mountain, literally the opposite side as the current Observatory. The picture below shows an aerial view of the summit from several years ago. Circled in pink is where the Stage Office is. Circled in yellow is the current location of the wind instruments.

There is actually a very important reason I bring this up. Remember from the previous parts of this discussion that the Big Wind came from the southeast. This wind coming from the southeast is going to have a certain upward trajectory as it accelerates up and passes over the summit. The likelihood of measuring the full strength of a southeast wind with this certain trajectory is much better on the southeast quadrant of the mountain. So perhaps, if the Observatory had not been located in the Stage Office on April 12, 1934, the 231 mph gust would not have been measured. That is the hypothesis anyways. This summer, we will be installing anemometers on different parts of the summit, including the Stage Office, to see if there is a significant difference in wind speed at different places around the summit.

Now I will move on to talk about the anemometer used to measure this wind. Back in March, I described in detail the system that we currently use for daily wind measurements. That system originally designed and implemented in the 1940s, so a different system was used in 1934.

In those days, there was really only one type of anemometer available: cup style rotating anemometers. Whether you realize it or not, I am sure you have seen one of these at some point in your life. A cup style anemometer is what you would typically see measuring the wind just about anywhere. In fact, home weather stations even use this type of anemometer.

In 1934, the Observatory did use a cup style rotating anemometer, however it was designed specifically for Mount Washington. It was constructed in Cambridge, MA and tested at the Guggenheim Aeronautical Laboratory of the Massachusetts Institute of Technology(MIT). The instrument was heated to prevent icing, much like the system we use today. It was mounted high above the roof of the Stage Office as shown in this very old picture:

The exact instrument that measured The Big Wind is actually in our museum here on the summit. Here is a picture of that anemometer in its case in the museum:

Each time this anemometer made a full rotation, a click was produced that the observers inside the building could hear through a speaker or earphones. The observer would count the number of clicks in a given amount of time, using a stopwatch. A wind speed could then be determined, and necessary corrections were applied.

In case you were wondering, no, the anemometer never blew away. This is a complete myth that a lot of people understand to be reality, unfortunately. After the storm, the instrument was taken down and tested by the National Weather Bureau and the measurement was determined to be valid.

The fourth and final part of this series will take a look at some of the common myths and frequently asked questions regarding the world record wind.