Determination of cloud water acidity at a mountain observatory in the Adirondack Mountains of New York State

A ground-based, cloud water collection system capable of intercepting significant volumes of water from clouds has been in operation at a mountain field station in the Adirondack Mountains of New York State for three summer seasons. An analysis of cloud water pH for August–September 1977 and 1979 strongly suggests that acid input to the ecosystem due to clouds at Whiteface Mountain may be significantly more important than that due to the much-discussed phenomenon of acid precipitation. The mean pH of nonprecipitating clouds was 3.55 during 1977 and 3.50 during 1979; approximately 90% of all observations were found in the pH interval between 2.66 and 4.66. In the event that precipitation is intercepted concurrently with cloud droplets, a minimum dilution of the cloud water acidity by a factor of 60–80% can be expected. Other aspects of the collection and pH analysis of cloud water at Whiteface Mountain are also discussed.