OLD SOL: Does it seem like we never get our fair share of sunshine? You’re right. We don’t.
Brad Ottum of McKeanWeather.com tells us we are doomed to get more cloudy days thanks to the Great Lakes, our geographical location and the earth’s rotation.
How could the lakes be a factor? Brad explains, “Evaporation, a very important part of the global water cycle, can be defined simply by solar radiation hitting the surface of a body of water and changing that water to a gas. That gas is then lifted into the atmosphere, which in turn can cause clouds to form.
“Anywhere in the northern hemisphere, there’s a prevailing west to east ‘wind’ just from the rotation of the earth, and coupling it with the rise of the liquid gas off the lakes, we get more than our share of cloudy days.”
Many of the National Weather Service recording stations, normally at airports, have phased out the use of sun sensors beginning in the 1990s. Now, to get data about how much sun we get, they use a system of clear, partly cloudy and cloudy.
For instance, Erie gets 63 clear days a year, 97 partly cloudy days and 205 mostly cloudy days. Pittsburgh’s average is 59, 103, 203. Buffalo at 52, 102 and 212.
Bradford joins the list with 73 clear days, 107 partly cloudy, and 185, mostly cloudy.
These are just averages of reported cloud cover over the last 20 years or so, depending on exactly when that station quit using a sun sensor.
At McKeanWeather.com, Brad uses equipment which still records actual hours of sunlight using the formula from the World Meteorological Organization W/m2 (watts per square meter). Their recommendation is for 120 watts and the Davis uses 110 watts, to give us actual hours of sunlight through each day.
“In ‘gardener’s terms,” he writes, “it’s enough sunshine to cast a shadow of yourself or any object, such as a tree, onto the ground.”
Brad has 2,902 days in his database, just short of eight years, and through those days, we average 4.84 hours of sun per day. Now, it’s not everyday we get sun as seen above, but across an entire year and its different seasons and hours of sun possible, that’s the average.
“So there’s good reasoning that after a long winter and heading into the springtime, we in this area are clamoring for some sunshine, with the lakes as our neighbors,” he writes.
