Blue Hill Meteorological Observatory

A private observatory

Abbott Lawrence Rotch, a Boston meteorologist, built the observatory on Great Blue Hill in Milton, Massachusetts, at his own expense, and regular observations began on 1 February 1885. The hill, 195 metres high, gave an exposure outside the city, and the record that began that day has continued without a break.

Rotch's interest was the upper air, which could not yet be observed. He turned to kites.

Kites in the upper air

On 4 August 1894 the observatory made the first atmospheric sounding by weather kite, using a design adapted from the box kites of Lawrence Hargrave. Kites carried meteorographs, recording thermometers, barometers and hygrometers, to heights of several kilometres, and gave routine profiles of the temperature and wind in the atmosphere until aircraft and balloons replaced them. The Blue Hill programme was among the first to treat the atmosphere as a three-dimensional system.

Rotch died in 1912 and bequeathed the observatory to Harvard. Under Charles Brooks and later directors it became a centre of climatology and cloud physics, and in 1938 its instruments recorded a gust of 186 miles per hour during the Great New England Hurricane.

After Harvard

Harvard withdrew from the site in 1971. The observatory was designated a National Historic Landmark in 1989, and in 2017 the World Meteorological Organization named it a WMO Centennial Station, recognising more than a hundred years of continuous observation. The Blue Hill Observatory & Science Center now runs it as an observatory, museum and education centre.

A long record with a private origin

The Blue Hill record illustrates how a private enthusiasm can become public infrastructure. Rotch paid for the instruments and the building, and the Harvard bequest gave an academic home to the continuing observations. The records from 1885 allow the climate of eastern Massachusetts to be set against the growth of Boston, and the early kite soundings are a rare quantitative record of the upper air before the radiosonde. The observatory's modern role is as a science centre and a reference: it still reads the instruments of the original programme, so that the record is unbroken, in parallel with automatic stations.

Instruments and technologies

• Box kite with meteorograph A Hargrave-type box kite flown on piano wire carried a recording instrument that traced temperature, pressure and humidity on a smoked drum or paper.
• Anemometers Cup anemometers on the summit tower recorded wind speed continuously; the 1938 gust was measured on one of them.
• Standard weather instruments Thermometers in a shelter, a barometer and rain gauges with an hourly observing programme.

The people

• Abbott Lawrence Rotch Founder; pioneer of upper-air observation with kites.
• Charles Brooks Director and climatologist.
• William Eddy Kite flier and kite designer.

Timeline

• 1885 Regular observations begin on 1 February.
• 1894 First atmospheric sounding by weather kite (4 August).
• 1912 Rotch dies and bequeaths the observatory to Harvard.
• 1938 Records a 186 mph gust in the Great New England Hurricane.
• 1971 Harvard withdraws from the site.
• 1989 Designated a National Historic Landmark.
• 2017 Designated a WMO Centennial Station.

Key lessons for observation today

• Measure the third dimension Kites gave profiles of the air above the hill. Surface stations are only half a weather network; vertical profiles are the other half.
• A private start can become a public record A founder's funds began the series; a university and later a science centre kept it. Long records need a succession plan.
• Document extremes with the right instrument The 186 mph gust is credible because the instrument and exposure are known. Extremes need calibrated, documented sensors.

Sources

• Wikipedia, Blue Hill Meteorological Observatory
• Blue Hill Observatory & Science Center, Overview
• Blue Hill Observatory, Go Fly a Kite. Seriously, It Was Science.
• National Park Service, Blue Hill Meteorological Observatory