By Greg Lecker
The clearing skies this morning fool me into under-dressing. And, most odd, the air temperature seems to have fallen somewhat even as the sun has risen. Air temperature is not increased by the sunlight striking it. For the most part, sunlight passes straight through the atmosphere and is absorbed by the ground. It is the warming of the ground by sunlight that in turn warms the air because the air is in contact with the ground. This explains the lag between the sun’s rising and an increase in air temperature as the day begins. The temperatures will have “soared” from zero degrees at the start of my walk to ten degrees at the end.
Even the animals appear to be sensing the crisp coolness this morning. Several turkeys have huddled next to the feeders, actually sitting on the snow, belly to the snow. Two others stand on one leg. A cottontail rabbit hops amidst the brush near the entry to the woodland.
Throughout the Grace Dayton Wildflower Garden, the ground is a uniform white form now. There is no sign of the woodland brook and the small pool deep within is frozen and snow covered. I make a quick trip through the zig-zag path on my way to the prairie.
It’s brighter out in the open. The breaking sun filters through the comb of tree trunks and illuminates the top of an Austrian pine.
Beyond, the waning moon is setting through the outstretched fingers of bur oak boughs. Below, there are frost crystals on prairie plant seed heads and the rose hips.
Today’s frost takes not the form of a dusting nor the grace of six-sided snowflakes but the coarseness of sea salt. I recall a graph explaining the effect that temperature (and likely moisture too) plays in the shape of frozen water as it settles out of the air.
It’s too early for others on Three-Mile Drive which is only lightly covered with remains of snow and ice. On my return through the woodland, I notice hoof prints from a White Tailed Deer that has navigated a path bordered by handrail. The Arboretum is wise to exclude these inquisitive foragers from the display gardens nearest the visitor center. Sunlight rakes across the undulating mess of snow covered plant matter.
Chilled to the bone I retreat to the welcoming buildings where I especially enjoy the warmth of the conservatory.The orchids there are as colorful as the current exhibit of the Arboretum Photographers Society, on display through April 2. Make a point to see both on your next visit.
Greg Lecker is a Minnesota Master Naturalist Volunteer.