Ben Nevis Observatory

For twenty-one years, from 1883 to 1904, observers climbed Britain's highest mountain to read thermometers every hour, day and night, in all weathers. The record, and the lessons about the free atmosphere, outlasted the building.

A case for a summit station

In 1877 David Milne Home of the Scottish Meteorological Society proposed an observatory on the summit of Ben Nevis, 1,345 metres high, to study how weather behaves above the valleys. The meteorologist Clement Wragge climbed the mountain daily in the summers of 1881 and 1882 to take readings, which showed what could be done and what it cost. The observatory formally opened on 17 October 1883.

Observers recorded temperature, pressure, humidity, wind, rainfall, sunshine and cloud at hourly intervals, day and night, throughout the year, in a building where the summit's mean temperature was a little below freezing and fog was frequent.

Two stations at once

In 1890 a second, low-level observatory opened at Fort William in the valley, so that the same instruments could be read at the same hours at sea level and at the summit. The comparison showed how temperature and humidity change with height, and gave early evidence of how depressions pass over the mountain.

The summit also gave science an unexpected gift. In September 1894 the young physicist C. T. R. Wilson spent a few weeks on the summit and saw a glory and coronas, optical effects of cloud droplets; wanting to reproduce them in the laboratory, he built the apparatus that became the cloud chamber, for which he shared the Nobel Prize in Physics in 1927.

Closure and rescue

Both observatories closed in October 1904 for lack of funding. The ruins remain on the summit, and the paper records were kept in Scottish archives. In recent years, volunteers have transcribed the hourly records as part of citizen-science weather rescue projects, so that they can be used in climate research.

What the records taught

The twenty-one years of hourly records were studied at length. They showed how the temperature and pressure on a mountain follow the free atmosphere above and revealed the passage of depressions and anticyclones. They informed the design of later mountain stations. The cost was high: observers lived in cramped quarters in a cloud for most days, and the observatory's income of subscriptions and grants was never secure. Today's automatic stations on Alpine and Scottish summits do the work with less hardship, but cannot replace observers' notes of what the weather looked like.

Instruments and technologies

  • Hourly thermometer and barometer readings Mercury barometers and liquid-in-glass thermometers in screens, read by hand every hour by observers living on the summit.
  • Paired stations The Fort William station, from 1890, repeated the hourly programme at sea level to give a direct comparison.
  • Rain gauge, anemometer and sunshine recorder A standard set of meteorological instruments on the summit, with the anemometer exposed to the summit's gales.

The people

  • David Milne Home Scottish Meteorological Society figure who proposed the observatory.
  • Clement Lindley Wragge Meteorologist who climbed the mountain daily in 1881 and 1882.
  • C. T. R. Wilson Physicist inspired by a glory seen from the summit to build the cloud chamber.

Timeline

  • 1877 David Milne Home proposes a summit observatory.
  • 1881 Clement Wragge climbs the mountain daily to take readings.
  • 1883 Observatory formally opens on 17 October.
  • 1890 Full low-level observatory opens at Fort William.
  • 1894 C. T. R. Wilson works briefly at the summit and sees a glory, later inspiring the cloud chamber.
  • 1904 Both observatories close in October for lack of funding.

Key lessons for observation today

  • Run the pair, not the single site A summit and a valley station together showed vertical structure that neither could alone. Paired reference sites are still the best way to test a new location.
  • Observers matter Hourly observing in severe conditions needed a living team. Remote automated stations now take over such sites, but only with strong maintenance planning.
  • Rescue the records Paper records from 1883 are now being transcribed. Data rescue and digitisation extend the value of old networks.

Sources

  • Wikipedia, Ben Nevis
  • ScotlandsPeople (National Records of Scotland), Our records: Ben Nevis Observatory
  • Royal Meteorological Society, Ben Nevis Weather Observatory and Operation Weather Rescue