Some Data on the Meteorology of Wind Cave
Robert F. Brown - Expedition Meteorologist
The study of cave meteorology includes the investigation of such phenomena as temperature, relative humidity, barometric pressure, and air movement of the cave atmosphere and their variation in space and time. Wind Cave is well knwon for its complicated air movements. To investigate these parameters, recording instruments were placed in various locations in the cave and data were collected for approximately 10 days. All instruments were loaned to the expedition by the NSS Equipment Committee from its stock of ONR-contributed apparatus.
The observation stations and their devices were:
- Surface - barograph, thermograph
- Pearly Gates - barograph, hygro-thermograph
- Elks Room - barograph, hygro-thermograph
- Bottom of elevator - barograph, hygro-thermograph
- Cathedral Room - hygro-thermograph
- Model Room - hygro-thermograph
- Post Office - thermograph
The complete records from these stations are included in the figures of this report.
The barograph records show variations of 10 to 15 millibars in a roughly periodic fashion. The periods, however, are greater than the di-urnal period. The cave records for the most part mirror the surface record except that lag times of up to several hours are observed.
The thermograph and hygro-thermograph records show little variation during the period of observation. This is to be expected since the di-urnal temperature fluctuations are damped by the thermal lag in heat transfer through the overlying rock and only seasonal fluctuations are likely to be observed. The Elks Room record shows a temperature increase from 50° F to 54° F during the 10 day observation period. All other records remained constant.
Temperatures do vary from one part of the cave to another. The varition between the observation stations are given below:
- Model Room 49° F
- Bottom of elevator 50 ° F
- Cathedral Room 49° F
- Post Office 48° F
- Elks Room 51° F
- Pearly Gates 53° F
Relative humidity in the lower levels were 100% to within the percision of measurement. The exception was the bottom of the elevator where the relative humidity was 93%, possibly as a result of a pumping in of surface air by the elevators. In the Pearly Gates the relative humidity was 96%. Thus only in the higher levels of the cave would evaporation be likely to play a role in mineralization.