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How is this year’s Atlantic hurricane season measuring up?
The Atlantic hurricane season is now more than two months old and has so far been fairly quiet with only three storms — all of them in the weakest category of tropical depression. This may well have been the case in the summer and fall of 1492 as well.
It is interesting to note that among the seemingly endless list of superstitions and fantastical falsehoods that surrounded voyages of exploration in the age of discovery — ranging from sea serpents of all kinds to boiling waters near the equator — there was no mention of hurricanes. This is obviously because no European had yet witnessed (and could not imagine) the frothing seas, with towering 100 foot waves, that these ferocious storms can create. Continue reading
Can dust from Africa reach the United States?
Yes. Soil-derived aerosols, or dust, are abundant in our atmosphere. One source of dust is sandstorms over the Sahara. These storms whip small pieces of mineral dust from the desert into the atmosphere. Easterly winds then carry large plumes of Saharan dust away from the desert and over the Atlantic Ocean.
This weather system is referred to as a Saharan air layer, or SAL, and at times dust in the SAL has traveled to the Caribbean, Texas and Florida. Desert dust from the Sahara and Gobi deserts has been observed on the ice sheet of Greenland. Ice cores in Greenland provide a history of the dust deposition as it appears as layers in the ice. Continue reading
Category: Climate, Meteorology, Seasons
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What are the wettest and driest days of Madison’s warm season?
All things considered, we have really had a rather benign summer in southern Wisconsin thus far this year. Through Friday of last week, July was averaging just over 1 degree warmer than normal, with the majority of the contribution to this slightly warm month coming in the overnight lows, which have been 1.5 degrees above normal thus far. In addition, except for the 1.23 inches of rain we received when the heat broke July 23-24, we would be just about normal for July.
Somehow we got thinking about some characteristics of warm-season (May through October) precipitation in Madison in the midst of this spell of fine summer weather. Dr. Ed Hopkins at the State Climatologist’s Office was on the ready for our question, which was: What are the wettest and driest calendar days during the warm season in Madison? By “wettest” we mean the calendar day on which the most total accumulated precipitation has been recorded in Madison’s 153-year climatological record — and the least for the “driest” day. Continue reading
Are heat waves increasing?
A heat wave is a period of abnormally and uncomfortably hot and usually humid weather.
The World Meteorological Organization is specific in its definition by stating that a heat wave is when the daily maximum temperature for more than five consecutive days exceeds the average maximum temperature by 9 degrees. Continue reading
What causes lightning?
Charges form in a storm composed of ice crystals and liquid water drops. 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. Continue reading
