Category Archives: Phenomena
Thursday night and Friday morning, several people reported hearing loud noises, thinking something fell on their house or gunshots were fired.
These sounds result from what are called frost quakes or ice quakes. They occur when a rapid drop in temperature leads to a quick freeze. Continue reading
Thus far the winter has been relatively mild around the Northern Hemisphere. This December was the 14th-warmest December, and the period from Sept. 1 through Dec. 31 was the eighth-warmest since 1948.
Such a prolonged delay to the onset of winter makes one wonder if it will ever arrive this year. Though there is no clear way to be sure about the answer to that question, one potential phenomenon that can encourage a winter-like cold air outbreak is a sudden warming of the lower stratosphere, the layer of the atmosphere between 6 and 20 miles above the surface. Continue reading
In 1803, British pharmacist and chemist Luke Howard devised a classification system for clouds. It has proved so successful that meteorologists have used Howard’s system ever since, with minor modifications.
According to his system, clouds are given Latin names corresponding to their appearance — layered or convective— and their altitude. Clouds are also categorized based on whether they are precipitating. Continue reading
The atmosphere is actually a fluid. Like water, the pressure at the bottom of a deep column of fluid is larger than the pressure near the top of the column.
Fluids move in response to differences in pressure (the pressure gradient force), always flowing from high toward low pressure. In fact, the wind is driven by pressure differences measured in the horizontal directions. Therefore, the air near the ground (at the bottom of the deep atmosphere) is compelled to move upward toward lower pressure above. Continue reading
El Niño is a combined atmosphere/ocean circulation anomaly in the tropical Pacific Ocean in which unusually warm surface water extends westward from the coast of Peru into the mid-Pacific. One is predicted to develop this winter, which may impact our winter weather.
The warmer than normal waters support persistent tropical thunderstorms in that same region — where such storms are ordinarily rare. Continue reading