MANY SIMILARITIES AND SOME NOTEWORTHY DIFFERENCES IN COLD-AIR TRAPPING MECHANISMS AT ALGIFIC TALUS SLOPES, ROCK CITIES, AND CAVE PASSAGES IN THE CENTRAL APPALACHIANS

Hourly Hobo data logger measurements at Ice Mountain algific talus slope (over 14.3 years), Little Beartown rock city (8.6 years), and Crowder Cave (5.6 years) show many strong similarities and some significant differences in air-flow mechanics at three different types of cold air traps in West Virginia. Temperature data indicate all are open systems abruptly disrupted by cold density currents during cold weather, but become nearly closed systems due to density stratification during warm weather. Temperature data support a natural refrigeration model articulated by Hayden (1843) and popularized by Balch (1900) wherein sinking cold air dominates other circulation. Although local instances of upward secondary chimney effects have been documented at Ice Mountain, two-way air-flow circulation appears less significant than proposed by Frest (1981; 1983) for algific talus slopes in Iowa. Mean annual temperatures range from 1 to 3°C at our sites, 8 to 10 C° colder than nearby weather stations.

All three cold air traps respond rapidly to cold weather; temperatures may drop up to 12 C° (up to 8 C° at Crowder Cave) overnight, and the timing of site temperature minima usually lag only 1 to 2 hours behind nearby atmospheric temperature minima. In contrast, late spring and early summer warming typically is just 0.05 to 0.2 C°/day and only weakly correlated with outside air temperatures. Over our periods of record, standard deviation of hourly temperatures at Ice Mountain talus slope and Little Beartown rock city is ~ 5 C°, half the standard deviation of ambient air temperature data. Standard deviation in the two coldest rooms at Crowder Cave is 3.5 to 4.0 C°, illustrating a smaller amplitude of temperature change in almost all seasons, most likely because the cave has much greater void space volume than the other sites. All three experience complex winter ice accumulations that persists long after snow disappears from surrounding landscapes. Historical accounts from the three sites note that ice lasted into late summer; much later than has been observed during our study. General air-flow mechanisms are likely to remain intact under ongoing climate change, but possible increased snowfall may offset expected increases in rainfall and temperature, so specific long-term consequences may differ between the three cold-air traps.