Temperature & Humidity

Eastern PipThe temperature of a cave is directly related to the outside temperature. The thermal mass of bedrock and soil is incredibly high. This is most evident during the spring when the ground thaws after cold winter. Deeper underground the rock temperature will slowly adjust to average air temperature changes but this process takes many years. Because the change is so slow, we find that the ground temperature is approximately equal to the average annual surface temperature. In other words, if you know the average daily temperature (in a 24 hour period) for each day of the year, add them all together (365 temperatures) and divided by 365 (number of days in one year), you will arrive at the annual average temperature. This number is approximately equal to the temperature in the cave, or ground temperature. This temperature will be influenced by where the cave is located both in altitude and where on the earth. The average temperature of caves in Texas is close to 70 degrees. Our cave is at 49-50 degrees.

Wisconsin caves will average from 49-52 degrees depending on where in the state the cave is located. Crystal Cave can have temperature fluctuations of as much as two degrees depending on where you are in the cave and what the atmospheric conditions are at that time (more on that, later). Contrary to popular belief, the Refrigerator Room is not any colder than the rest of the cave.

The temperatures of pools of water in the cave will also be equal to the temperature of the cave air. Any water entering the cave will be warmed or cooled to the cave temperature. The water dripping from the ceiling of the cave is 49 degrees.

Cave Humidity

The air in Crystal Cave is essentially saturated with water vapor which makes the relative humidity close to 100%. This high humidity is the result of moisture (water and carbonic acid) constantly seeping through the roof, walls, and floor of the cave. The constant temperature of the cave allows the high humidity to be maintained indefinitely.

The only place humidity may be slightly lower is on the first and second levels. This is because the outside humidity is usually lower and the air on these two levels can be diluted through mixing with surface air.

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