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What is lake effect snow?
Lake effect snow forms when cold air passes over the warmer water of a lake. As cold air moves over water, the lower layers are warmed and moistened by the lake below. This makes the air mass unstable. Evaporation increases the moisture content of the air mass, which is then precipitated in the form of snow on the land downwind.
Maximum heat and moisture exchanges occur when the air is cold and the temperature difference between the air and the water is large. This condition tends to occur during early winter; this is when the most lake effect snow is produced. A long path across warm water by the air mass results in heavy precipitation over the land. Continue reading
What is a November gale?
A gale is a sustained wind between 39 mph and 54 mph. Gales are usually caused by large differences in the air pressure between a low pressure system and a strong high pressure system. Gale winds are common in November on the Great Lakes.
This week marks anniversaries of some strong November gales in the Great Lakes region. The most famous of these include the White Hurricane (Nov. 7-10, 1913), the Armistice Day Blizzard (Nov. 11, 1940), the Edmund Fitzgerald Storm (Nov. 9-10, 1975) and the storm Nov. 10-11, 1998. Continue reading
Does lightning travel from the sky downward or ground upward?
Lightning is a huge electrical discharge that results from vigorous motions that occur in thunderstorms.
Lightning can travel from cloud to cloud, within the same cloud, or between the cloud and ground. In-cloud lightning discharges are more common than cloud-to-ground discharges and are not as hazardous. Cloud-to-ground is the best known type of lightning and it poses the greatest risk. Continue reading
Category: Meteorology, Phenomena, Severe Weather
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What is a haboob?
A haboob is dust storm that can be several miles long, several thousand feet high, and can travel hundreds of miles. Haboobs are caused when an intense column of sinking air in a thunderstorm hits the ground and lofts soil particles into the air. These downdrafts, referred to as a microburst, can hit the ground at 50-80 mph and then spread in all directions. The resulting winds stir up dust and dirt from large arid areas which then get blown along in front of the approaching thunderstorm. The lofted particles can reach heights of 5000 ft and can extend up to 100 miles wide.
The name “haboob” is derived from the Arabian word ‘hab’, meaning ‘to blow,’ and was originally the name for a dust storm or sandstorm in the northern part of Sudan. Continue reading
What is the longest lightning bolt?
Lightning is a huge electrical discharge, or spark, that results from vigorous motions in thunderstorms.
Storms are composed of ice crystals and liquid water droplets. Winds inside the storm cause particles to rub against one another, causing electrons to be stripped off, making the particles either negatively or positively charged. The charges get grouped in the cloud, often negatively charged near the bottom of the cloud and positively charged up high. This is an electric field, and because air is a good insulator, the electric fields become incredibly strong. Eventually a lightning bolt happens, and the flow of electrons neutralizes the electric field. Continue reading
Category: Meteorology, Phenomena, Severe Weather
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