The Weather Guys

Punxsutawney Phil saw his shadow, which means there will be six more weeks of winter. On the other hand, Jimmy the Groundhog in downtown Sun Prairie did not see his shadow at sunrise during the 78th annual Groundhog Day Prognostication, which per tradition means we are due for an early spring. Which to believe?

We don’t put stock in either.

Humans have long needed weather forecasts. Farmers and sailors particularly needed to know if storms were approaching. Over time, various folklore forecasts, often in the form of short rhymes, were devised and passed down through the generations. The forecast made on Groundhog Day is an example of a folklore weather forecast. Although memorable, the folklore forecasts are of uneven quality — some good, others bad.

The roots of Groundhog Day go back to the sixth century. Feb. 2 is 40 days after Christmas and is known as Candlemas. On this day, candles that are used for the rest of the year are blessed. This is also about the midpoint of winter, in astronomical not meteorological terms. If the day is bright and clear, the groundhog “sees” his shadow and we have more winter.

Of course, after Feb. 2, there are only 47 days left of astronomical winter — which ends on or about March 21, so the forecast accuracy should be more than luck. The predictions made by Punxsutawney Phil with this folk forecast are correct only about 40% of the time, and Jimmy the Groundhog is about 60% accurate — both vastly inferior to what is delivered by modern science.

Of course, the weather conditions on a single day at a single location tell us very little about the weather for the rest of the winter season. But right or wrong, they are fun community celebrations, as well as an entertaining movie.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at noon the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.

Colds and the flu are caused by viruses, not by cold wintery conditions. Viruses such as rhinoviruses, which cause the common cold, and influenza viruses spread from person to person through respiratory droplets or physical contact, regardless of the temperature outside.

However, weather and climate do play a role in why colds and the flu are more common in winter though. The colder temperatures associated with winter affect how viruses behave in the environment. Winter’s colder temperatures and lower humidity help viruses survive longer and spread more easily. Research studies show that many respiratory viruses survive longer and remain infectious for extended periods of time in cold, dry environmental conditions.

Dry air also causes tiny droplets released when people breathe, talk, cough, or sneeze to evaporate quickly. These droplets evaporate quickly, creating smaller particles that stay suspended in the air longer and travel farther, increasing the chance that others will inhale them.

Winter’s low humidity can dry the lining of one’s nose and throat. This reduces the effectiveness of mucus, which normally traps viruses and helps move them out of the airways.

In cold weather, social events tend to be indoors, bringing us in close contact with others.  This increases the chance of the spread of a virus. Preventive measures such as vaccinations, good hygiene practices, and wearing masks in crowds help to reduce the risk of viral infections. Improving indoor ventilation and maintaining adequate humidity during winter can also reduce transmission risk. Cold weather can be challenging for people with existing respiratory conditions such as asthma.

Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at noon the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc. edu.