Blue Hill Observatory Field Trip

Posted by Richard Primack

“A regular snowstorm has commenced, fine flakes falling steadily, and rapidly whitening all the landscape. In half an hour the russet earth is painted white even to the horizon. Do we know of any other so silent and sudden a change?” 

Henry David Thoreau, November 28, 1858

On February 6, the Boston University Biogeosciences Program had a field trip to the Blue Hill Observatory, the longest running weather station in the United States. The Observatory was established in 1884 on a hill 10 miles south of Boston. We often use data from the Observatory in our research to determine if long-term phenological patterns are affected by temperature and rainfall. The Blue Hill Observatory is uniquely useful for our purposes because its scientists have incorporated earlier weather observations into their records, extending temperature data back to the 1830s and overlapping Henry David Thoreau’s phenology observations from Concord. For us, the key finding of the Observatory is that the temperature of Boston has been getting warmer over the past 133 years.

The Blue Hill Observatory with weather instruments on top:

At the base of the Observatory, BU post-doc Eli Melaas explains the function and history of various instruments. To his right is a designated spot that is regularly cleaned off to record the amount of snowfall and the rate of snowfall:

This rain gauge has a perimeter of flaps to create wind turbulence and create a more standardized measure of precipitation. The Blue Hill Observatory is a pioneer in developing and improving weather instruments:

On the roof of the Observatory, sunlight intensity is recorded when sunlight focused by the glass ball burns holes in a standard paper sheet as the sun traverses overhead during the course of the day:

A special feature of the Observatory is that it uses both the original equipment and more modern equipment in order to provide continuity in its measurements. Here are the original barometers that are still used to record air pressure:

Wind speed from the anemometers on the roof is recorded on a moving sheet of paper inside the Observatory: