ELMIRA, N.Y. (WETM) – Radiation fog is no stranger to the Twin Tiers, especially during the fall and winter months. It is common during the overnight hours when cooler air moves into the region and the air near the ground cools off and reaches saturation. This is common after some rain during the day and the ground remains wet. The cooler air near the moist ground will reach saturation much quicker, creating dense fog. This fog will continue to extend upward as the air above the fog also reaches saturation. Once the sun rises, most of it will burn off rather quickly. How fast it does depends on how much fog developed overnight.
There are two things that favor this type of fog developing. The first is a valley that is sheltered. This is very common around the Twin Tiers as we have many hills and mountains surrounding numerous valleys. This protects the air and allows for it to not be disturbed, therefore allowing this fog to form. Another ingredient that allows for this fog to form is calm winds. Any wind that develops runs the risk of breaking up and dispersing the fog that forms. However on a calm night, this fog is allowed to really thicken and rapidly form.