ASK TOM: Why are people who predict and report the weather called meteorologists?

Dear Tom,

Why are people who predict and report the weather called meteorologists? Meteors are rarely mentioned.

— Jack, Orland Park

Dear Jack,

It’s been a while since we’ve addressed this question. The derivation of many English words can be traced back to ancient languages and cultures.

The word meteorology dates back to ancient Greece — around 340 B.C., when Aristotle wrote “Meteorologica,” which covered that era’s knowledge of weather and climate along with related disciplines of geology, astronomy and oceanography. He was interested in observed atmospheric phenomena such as clouds, rain, snow, thunder, wind and rainbows. Ancient Greeks referred to any particles suspended or falling through the air as meteors; the terms meteorology and meteorologists came from his work.

ASK TOM: The late-season snowstorm of April 2-3, 1975

Dear Tom,
I remember an April snowstorm in either 1974 or 75 that clogged expressways, stranding many on their way home from work. Do I remember correctly?
— William Meyer

Dear William,
You’re thinking of the late-season snowstorm that blasted the Chicago area on April 2-3, 1975, with the official snowfall total of 9.8 inches at Midway Airport. Snowfall was even heavier to the north and west where 11 inches of snow closed O’Hare International Airport and more than a foot piled up in some north and northwest suburbs.

The storm came as quite a shock to Chicagoans as it followed more than a week of mild spring weather that included highs of 74 on March 21 and 62 on March 31. The snow, which began as a mixture of rain and sleet, was heavy and wet; at least eight people died of heart attacks while shoveling.

ASK TOM WHY: How did the storm that wrecked the Edmund Fitzgerald affect Chicago?

Dear Tom,

I was driving yesterday when I heard the Gordon Lightfoot song the “Wreck of the Edmund Fitzgerald”. How did that storm affect Chicago?

Art Azen

Dear Art,
The Edmund Fitzgerald sank in a legendary late autumn storm on Lake Superior about 17 miles northwest of Whitefish Point, Mich., on Nov. 10, 1975. As cold air swept across the lake in the storm’s wake, west winds reached 80-90 mph, speeds equivalent to a Category 1 hurricane. The high winds generated 25-30 foot waves that proved too much for ship, which took its crew of 29 to a watery grave. Chicago was in the warm sector of the storm and received some rain and thunderstorms. Gusty south winds to 46 mph boosted the mercury into upper 60s and lower 70s but in the wake of the storm temperatures crashed into the lower 30s bringing the city its first measurable snowfall of the season.

ASK TOM: Describing the sound of tornadoes

Dear Tom,

“It sounded like a freight train” is a typical description of the sound produced by a tornado, but how did pre-industrial people describe it?

— Rich McConnell

Dear Rich,

Historical accounts in pioneer and Colonial times liken the sound of tornadoes to the hum of billions of bees, the roar of hundreds of waterfalls or the continuous boom of cannons.
Sound recordings with modern video cameras and similar equipment indicate the sound of a tornado would be more accurately described as a strange hissing or whistling similar to the sound generated by an open car window when the vehicle is traveling as a very high speed. Some tornado survivors say they could actually feel vibrations against their faces, causing a tingling or stinging sensation.

ASK TOM WHY: How much rain fell during May 6-11, 1960?

Dear Tom,

The Cubs had six straight rainouts from May 6-11, 1960 at Wrigley Field. How much rain fell during that period?

Orland Park

Dear Rich,

The only significant rainfall during that stretch was 0.41 inches of rain that washed out the first of the six postponed games with just an additional 0.18 inches falling during the next five days. The remaining games were canceled due to a combination of cold and light rain and drizzle as brisk northeast winds held temperatures at the ball park near 40 degrees. Cubs’ manager Lou Boudreau had just taken over the struggling team and welcomed the first couple of rainouts so his beleaguered pitchers could get some rest. After the sixth postponement Boudreau remarked that “…our pitchers are so well rested now, I’m afraid they’ll start to rust.”

ASK TOM: Snowed out White Sox Home Opener in 1982

Dear Tom, 

I distinctly remember a White Sox home opener in the early ’80s that was snowed out. Any records to back my claim as my friends are skeptical?

Terry Fenelon, Naperville

Dear Terry,

You bet. The 1982 Chicago White Sox home opener scheduled for April 5 fell victim to one of the biggest late-season snowstorms in the city’s history. The heavy, wet snow was a shock to many as it followed a six-day run of 60s from March 29 to April 3. Cold air swept into the city in the wake of a rainstorm and windstorm April 3 to 4, setting the stage for the snowfall. Northeast winds gusting to 40 mph piled the snow into huge drifts while dropping the visibility to near zero. Record cold followed the snow with the mercury plunging to 7 degrees April 7, the city’s only single-digit April temperature on record.

ASK TOM: Has Chicago ever experienced a day with the same high and low temperature?

Dear Tom,

Has Chicago ever experienced a day with the same high and low temperature?

— Isaac VanDeBerg, Barrington
Dear Isaac,
A Chicago day with the same high and low is extremely rare, with just one occurrence since Chicago weather records began in 1870. The lone day was Feb. 6, 1942, with a high and low of 35 degrees. It was a raw, damp and windy day, with brisk east-northeast winds gusting up to 40 mph. Heavy rain fell much of the day, eventually mixing with snow in the afternoon and night, with the day’s precipitation totaling 1.98 inches. The string of steady temperatures actually extended for 30continuous hours, from 9 p.m. Feb. 5 to 3 a.m. Feb. 7.

In sharp contrast, the day with the largest range between the high and low was Feb. 8, 1900, with a 52-degree span, from a high of 62 to a low of 10.

ASK TOM: What is the best temperature for snow?

Dear Tom,

What is the best temperature for snow?

— Jon Rosecrans


Dear Jon,

Snow can occur only when water vapor is present in air at subfreezing temperatures, a mechanism exists to chill that air below its saturation temperature, and there are conditions that allow tiny ice crystals to grow into snowflakes that can fall to the ground.

Airborne ice crystals spring into existence when water vapor condenses (technically, sublimes) at subfreezing temperatures.

But because the amount of water vapor that can be present in air increases dramatically with increasing temperature, the greatest amount of snow is possible in any given situation when the temperature (at the level at which snow is forming) is as high as it can be for snow to occur: 32 degrees.

ASK TOM: The difference between “Normal” and “Average” temps

Dear Tom,
What is the difference between “average” and “normal” temperatures?
— James Byrne, Lansing

Dear James,
By international convention, daily high and low temperatures are defined as the maximum and minimum temperatures that occur in the 24-hour period, midnight to midnight, local standard time. An average daily temperature is the sum of those high and low readings, divided by two.
The average temperature over a longer period of time, say March 1-31, is the sum of the 31 daily highs and the 31 daily lows, divided by the number of summed values (62 in this case). A “normal” temperature at a location is also an average temperature, but it’s a special average — calculated over a precise 30-year period, currently Jan. 1, 1981 to Dec. 31, 2010. New normals will be calculated when data become available for 1991-2020.

ASK TOM WHY: When was the last time Chicago had measurable snow in May?

Dear Tom,

When was the last time Chicago had measurable snow in May?

Mary, Geneva

Dear Mary,

Measurable snowfall in May is very rare in Chicago having occurred in only eight years dating back to 1885. Chicago climatologist Frank Wachowski reported that the most recent occurrences were 0.5 inches on May 6, 1989 and 0.1 inches on May 2, 1976. Most May snowfalls are minor, amounting to just a few tenths of an inch, but there have been a few exceptions. In 1907, 1.3 inches of snow fell on May 3, and in 1940 the Chicago area was whitened by a 2.2 inch snowfall on May 1-2 at the official downtown location while Midway Airport received a slushy 3.7 inches and some suburban areas measured as much as 5 inches. The snow quickly melted as temperatures rebounded into the 70s by May 5.