Finally. Your tulips are blooming and the robins are out on the lawn, pulling up worms. But remember last week when you were bundled up in a winter coat, there was frost on your windshield and you had this feeling?
Not actually sick, but a bit anxious? A little depressed?
There's a name for that general malaise you may have been suffering: weather stress. And a climatologist has come up with real data to confirm just how distressed (or comfortable) you are: the Weather Stress Index.
What is uncomfortable weather for you, of course, might seem mild--even comfortable--to an Alaskan. Consider last week, for example, when people in Anchorage were virtually basking at 32 degrees F. and Atlantans shivering at 30. The Weather Stress Index (WSI) takes what you are accustomed to into account.
Developed by University of Delaware Prof. Laurence S. Kalkstein, 35, and graduate student John M. Grymes, 26, the WSI indicates how a given day's "apparent temperature" (the temperature as perceived by individuals) differs from the average apparent temperature for that day in past years at the same location.
"It is assumed," writes Kalkstein in a National Oceanic and Atmospheric Administration (NOAA) bulletin, "that people are adjusted to the average condition in their region, and that they undergo increasing stress when apparent temperatures drop below normal in winter and rise above normal in summer.
"Thus, the WSI is defined as a proportion of days with weather more comfortable (or less stressful) than the day under review."
For example, the WSI for Washington on a day in January with a 10-degree apparent temperature might be 70 percent, which means that 70 percent of the days are more comfortable (less stressful) than the day in question.
That same 10-degree apparent temperature in Atlanta would have a WSI of 99 percent, meaning that 99 percent of Atlanta's days are less stressful than that one.
"The 10-degree apparent temperature in Washington," explains Kalkstein, "is colder than normal but not unbelievably severe, while a 10-degree apparent temperature in Atlanta would be so severe that activities would be curtailed, people would be absent from work, kids would stay home from school, cars wouldn't start, that sort of thing."
Kalkstein, an associate professor at Delaware's Center for Climatic Research, worked on the WSI project under a $125,000 grant from NOAA's Assessment and Information Services Center. He says his aim was "to develop an index that was better than those existing--the wind-chill index and temperature-humidity index--yet simple enough so that a layman can understand it."
In their research, Kalkstein and Grymes came across the work of Robert Steadman, a textile research engineer at Texas Tech, who has written widely in weather literature about apparent temperature. The problem: Steadman's research was so technical and complex he had to wire up his subjects to measure electrically their physiological reactions to different weather conditions.
"We simplified his research," says Kalkstein, "by coming up with our own formula based on some of his data. Our formula--we have one for the winter and one for the summer--has as inputs temperature, relative humidity and wind speed."
The index currently is available only in the monthly editions of NOAA's "Climate Impact Assessment: United States." The reports, which assess how weather and climate influence the economic sector, cover such things as employe absenteeism, human health and morbidity, commerce, transportation and tourism. They now go to 150 or so private-sector subscribers as well as a number of congressional offices and other government agencies.
Malcom Reid, director of NOAA's Climate Assessment Branch, says private-sector subscribers represent "a broad spectrum, including medical, academic, business and financial interests."
Kalkstein stresses that the goal of the index is to understand how people in general (as opposed to individuals) react to the weather.
"We're not here to tell people whether or not they should go to work," he says. "We're trying to understand how weather affects such things as absenteeism.
"If we know that a certain value will precipitate a 50 percent absenteeism rate on an automobile assembly line, we could tell that firm to shut down one line ahead of time at great savings to them."
Kalkstein and Grymes, who began the project about a year and a half ago, "hit the usual bugs developing the formulas. We had a couple of failures and made a couple of mistakes, human errors, but now the index is out and finished."
First appearing last August in "Climate Impact Assessment," the index is now published on a delayed rather than "real-time" basis. The assessment covering April, for example, will come out in May.
The next step is to develop the Weather Stress Index readings "instantaneously," says Kalkstein, "so I could give you today's right now."
Kalkstein is confident the index eventually will be published in newspapers and broadcast on radio and TV "as the wind-chill factor is today." The index and related weather stress maps may be transmitted on the national weather wires serving weather stations and the news media "within a year or so."
The four-panel maps under consideration would include the current week, the season to date, the preceding 30 days and possibly a forecast for the following week. In other words you may be able to see why you felt so lousy last month and you might consider postponing next week's report to the stockholders.
"We have to go before a special NOAA board that approves inclusion of this index on the weather wire," says Kalkstein, adding that his case for getting the index and maps on the wire "will be very strong."
NOAA and Kalkstein have been getting queries about the Weather Stress Index "from all over the place, as far away as Australia. Calls have come from psychologists, mental-health institutes, engineering firms that deal with employe absenteeism, the news media, even air-conditioning and heating firms."
Kalkstein, who until recently was on sabbatical and working at NOAA's Environmental Assessment Services Center, says he and Grymes realize the current index already needs some improvements:
"The great floods we just had in California and Louisiana brought on economic panic, but the current Weather Stress Index would consider conditions there to be normal since it only takes into account temperature, humidity and wind speed.
"We need to include a precipitation parameter for both snow and rain. We can't deal with extreme precipitation episodes right now."