Weather in caves tends to be very constant compared to surface conditions. Lehman Caves is 50 degrees Fahrenheit year round. The relative humidity varies between 90 and 100 percent. The closer a room is to the entrance, the more variation in temperature and humidity it will have. Most sizeable caves do have nearly a constant temperature, when the airflow is not sufficient to change the temperature of the cave. Limestone, in particular, does an excellent job of absorbing and dissipating heat, helping to regulate the cave temperature. The temperature of the bedrock is often just about the average year round surface temperature. Seasonal temperature variations at the surface do not affect the bedrock at the depth of most caves, including the limestone of Lehman Caves.
There is airflow at the 'ends' of the cave, including beyond the Talus Room. Airflow in Lehman Caves is caused by a chimney effect, air moving between entrances. However, the air may be traveling through very small cracks and vents that explorers would never be able to fit through.
Natural changes in most caves are usually very slow due to these near constant conditions. There are few large animals entering the passages in Lehman Caves. There are no rivers. It never rains underground. Airflow at its strongest is a slight breeze. Most of the cave is too deep to be invaded and changed by plant roots. The speleothems grow on a time scale that is difficult for humans to observe. This means that changes humans cause in caves will last much longer than might be expected by comparison to human caused changes to the surface. Even footprints, may last for centuries in caves.
Last updated: February 28, 2015