For those of us in the northern hemisphere, spring begins on the vernal (or spring) equinox, which this year occurs at 03:50 UTC (Coordinated Universal Time) on March 20; in the Eastern time zone, that translates to 11:50 pm EDT Thursday, March 19. Depending on the speed of the postal service and when you get around to reading this issue, spring may or may not have sprung for you. As I write this, we are still firmly entrenched in winter — this week has been a series of cold, gray, dreary days. I am eagerly looking forward to spring and all that it brings. In hopes that immersing myself in thoughts of spring will lift my mood, I set out to learn more about this season.
There are multiple definitions of spring. As most of us know them, the seasons are determined by the position of Earth relative to the position of the sun. The spring that starts at the vernal equinox (the moment at which the plane of Earth’s equator extended in all directions passes through the center of the sun) and ends at the summer solstice is known as the astronomical spring.
Meteorologists define the seasons based on average monthly temperatures — the warmest three months are summer, the coldest months are winter, and the periods between are spring and autumn. By this definition, the seasons vary according to region. In the U.S., spring consists of the months of March, April, and May, while in Australia, spring runs from September 1 through November 30.
The National Centers for Environmental Information (NCEI) explains the basis for these varying definitions: Because Earth travels around the sun in 365.24 days and an extra day is added to the calendar every fourth year, the exact date and time of the equinoxes (which define the start of spring and autumn) and solstices (which define the start of summer and winter) vary. In addition, the elliptical shape of Earth’s orbit around the sun causes the lengths of the astronomical seasons to vary between 89 and 93 days. These variations in season length and season start would make it very difficult to compare climatological statistics for a particular season from one year to the next. Thus, the meteorological seasons were born.
Spring, however you define it, has much to offer: Flowers bloom and trees sprout leaves, temperatures increase, the number of daylight hours increases — all of which combine to make it easier and more pleasant to take part in outdoor activities. Even the commute to and from work is — dare I say it — somewhat enjoyable (or at least not as onerous as in the winter).
A Gallup poll found that 36% of Americans say spring is their favorite season; 27% prefer fall, 25% summer, and just 11% winter. And each time Gallup asked the question (in 1947, 1960, and 2005), spring came out on top. Another public opinion polling organization, Rasmussen Reports, found similar results in its surveys. They also found that even though spring is the favorite season of about one-third of the respondents, roughly two-thirds say that the arrival of spring puts them in a good mood.
At AIChE, the hallmark of spring is the Spring Meeting and Global Congress on Process Safety. This year’s meeting has been postponed to August 16–20. For updates, visit www.aiche.org/spring. I hope to see you there.
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