Monthly Archives: December 2018
In testimony to the infectious appeal of the famous scenes memorialized by Nathaniel Currier and James Ives, prolific lithographers of the middle 19th century, there is an enduring obsession with snow at Christmastime.
A so-called White Christmas is officially observed anytime there is 1 inch of snow on the ground on Christmas morning, whether or not it is snowing at the time. 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