Recently the concentration of moisture and light winds just above ground level and lack of mixing with drier/warmer air aloft has resulted in the prolonged period of cloudiness that is expected to continue here for the next few days. In addition this time of the year with the approach of the Winter Solstice (Dec 21), the sun’s angle is nearing it’s lowest point in the sky, and our days are fast approaching the shortest of the year. No wonder December is tied with January as the cloudiest month of the year (we average only 40% pf possible sunlight).
- Because of the lower sun angle, sunlight passes through nearly 2.5 times more atmosphere in December than June, more widely dispersing the already depleted solar energy, as opposed to the more direct rays in June (950 units of energy received as opposed to 300 units).
- In the winter, the Albedo (measure of reflectivity) is much greater than in the summer (greener increased foliage absorbs the sun’s rays), whereas grey-colored surface reflects already weakened sun’s rays in the winter.