Monthly Archives: September 2023
This year, the autumnal equinox occurred on Saturday, Sept. 23, at 1:50 a.m. Central Time. During the equinox, the sun shines directly on the equator as its position moves from one hemisphere to the other. The word “equinox” is derived from the Latin word “aequus,” which means “equal,” and “nox,” which is the Latin word for “night.” During the 24 hours of the equinox, there are about 12 hours of day and 12 hours of night.
You may hear that daylight and nighttime are of equal length on the equinox. But during the equinox at our midlatitude location, there are approximately eight more minutes of daylight for two reasons: the sun’s shape and atmospheric refraction. Continue reading
A tropical cyclone is a rotating low-pressure system that has organized thunderstorms but no fronts. When a tropical cyclone’s maximum sustained winds reach 74 mph, it is called a hurricane. Hurricanes have never directly impacted the Upper Midwest region of the U.S.; however, the remnants of a hurricane or tropical storm have impacted the weather in the Midwest, including Wisconsin.
If a hurricane is particularly strong at landfall, it can move far enough northward to cause a significant rain event for areas in the Midwest. For the most part, such storms originally make landfall in Texas, Louisiana or Mississippi. These storms can be tracked by satellites or surface weather observations because they maintain an identifiable circulation pattern along their entire path. Continue reading
The National Oceanic and Atmospheric Administration (NOAA) operates weather satellites with instruments capable of locating fires and determining fire characteristics such as size and intensity. These satellites also are critical to observing and monitoring smoke from those fires.
NASA recently launched a new satellite instrument to monitor air pollution. The Tropospheric Emissions: Monitoring of Pollution, or TEMPO, was launched into geostationary orbit on April 6, 2023. TEMPO measurements join an international satellite constellation of observations that will track pollution around the globe. The instrument measures sunlight reflected off Earth’s surface and solar energy scattered by clouds and the atmosphere. Gases in the atmosphere absorb sunlight at particular wavelengths, and the measured color spectra is used to determine the concentrations of several gases in the air, including nitrogen dioxide. Continue reading
As it turns out, predictions of the coming weather are nearly exclusively dependent on the observed conditions of the atmosphere in the day prior to the forecast period. Continue reading