Even though temperatures have risen steadily over the past few months, we are just now getting into our astronomical summer. The astronomical summer begins on the summer solstice, the date when the northern hemisphere experiences its longest day. On this date, the Earth is tilted so that the tropic of cancer, located at a latitude of 23.5 degrees north, is in direct line with the sun, instead of at an angle. A big question people often have is, ‘why does summer start when the sun is at its closest, and not as temperatures begin to warm?’ The summer solstice is significant because this is the day at which the northern hemisphere receives the highest amount of the sun's energy. Days continue to get hotter after the summer solstice because the Earth is very good at retaining that energy, creating a delayed warming effect. When we hit this date and our summer season begins, plants’ and animals’ behavior will also begin to change.
Longer days mean that many plants photosynthesize for a much longer period. Besides the warming temperatures, this is why plants grow and thrive throughout the summer. More plant growth will bring herbivores to eat in places where they previously could not. Elk move higher in elevation to stay cooler, and find new feeding grounds. Some animals change their colors to better suit the seasons, much like how we change our wardrobe. The long tailed weasel is well known for changing its coat from white to brown in the summer. The white coat is actually quite a bit warmer and better insulating than the brown. Come summer, the brown coat blends in better with the bare ground and summer vegetation. Weasels do not determine their change in color from the temperature, but rather from the amount of daylight in each day. So by the summer solstice, all of our furry friends should be in their summer coats.
As the astronomical summer begins we will see less rain as our days become warmer and drier. In the winter months, the Eagle Valley sees 12 to 13 days a month of precipitation. In the summer, however, that number drops to only 4 to 9 days per month. But, since warmer days hold more moisture, and storms tend to be more intense, average precipitation stays constant. On average, the town of Avon, receives around an inch of water each month throughout the year. Summer also marks the disappearance of snow from Colorado’s peaks, and the rivers and creeks in our valley will start to get very low. The start of summer kicks off a lot of changes, not just for the people in our valley, but also the plants and many animals that thrive here.
Austin Averett was a naturalist at Walking Mountains Science Center working on his Master’s Degree in Interdisciplinary Science at Florida Institute of Technology.