Does it seem that we have had more sun this winter than usual? Off the top of my head I’d say “probably about normal”. Statistically we have seen substantially more sun.
November is statistically our cloudiest month. On average we see 11 days of sun in November. The definition of “sunny” includes mostly clear days and days partly sunny days, which is when cloud cover is 40-70% of the day. November 2019 Green Bay had 15 days of sun. December averages 12 days. December 2019 was 16 sunny days. In the month of January, Green Bay averages 15 sunny days. Half our January is overcast.
You would think the cities across the state would be about the same as far as sunny days per year. Nope. Wausau averages 262 sunny days per year. Green Bay, 190.
Nationally, the cloudiest state is Alaska. I don’t really count them as they are in a world of their own. The second cloudiest city in the US is Anchorage, Alaska. Anchorage experiences an average of 2,061.20 hours of sunshine annually. The city is often in darkness 76% of the year. December is often the darkest month in Anchorage with an average sunshine of 51.8 hours while the sunniest month is May with an average of 288.7 hours of sunshine.
Pittsburgh, Pennsylvania, tops the list of the cloudiest cities in the US. The city sees the sun for approximately 2,021 hours annually. Generally, it is cloudy in Pittsburgh for 77% of the year. In fact, it is the sixth-cloudiest city in North and Central America. November to January are the cloudiest months with the city recording at most 60 hours of sunshine.
Seattle and Columbus in Washington and Ohio respectively are the third and fourth cloudiest cities in the US. Portland, Oregon completes the list of the top five cloudiest cities in the US with an annual sunshine duration of 2,340.90 hours.
As far as sunshine, some statistics use a general observation of a day. Some count hours.
Why is a location cloudiest? There are reasons.
One factor is proximity to water and the size of the water. Ocean, lake, river, etc…The temperature of the water is a factor as well. it takes a lot more energy to heat water than air. That is another subject.
in November, much colder air masses spilling over the still unfrozen, relatively warmer Great Lakes and creates moisture that ends up downwind of the lakes. The water vapor then rises until it condenses into clouds and precipitation that we call lake-effect. The warmer, moister air immediately above the lake surface rises because it is less dense than the colder air above. For the northern part of the United States, November can be a rather gloomy month because the main jet stream winds are sinking south out of Canada as we inch closer to winter, causing increased stormy weather across the northern states. Also, the low angle of the sun this time of year makes it hard for low-level clouds and fog to evaporate or “burn off” as the day goes on. Fog doesn’t really “burn off”. The dew point and air temperatures separate as we get daytime heating.