Sea Science: by Jordanna Sheermohamed
“Spring forward; fall back.” It’s a mnemonic phrase to help us remember which way to reset our household clocks: an hour ahead in the spring, at the beginning of daylight saving time; and an hour back in the fall, when daylight saving time ends and standard time is resumed. (And, yes, it’s “daylight saving time” – without an “s” at the end of the word “saving.”) This practice was designed to maximize “daytime” hours by capitalizing on the sun’s generosity, which is lavish in the summer and frugal in the winter. Calendar-wise, daylight saving time in 2017 began Sunday, March 12, in the Northern Hemisphere and ends Sunday, Nov. 5. The inverse holds true for DST in the Southern Hemisphere.
The idea was first officially proposed in the late 19th century by New Zealander George Hudson in order to give people more sunlight in the late spring and summer, but his idea was not favored at the time. Germany was actually the first country to adopt the policy of sommerzeit (literal German for “summertime”) nationwide in the early 20th century. This was done to conserve fuel during World War I by extending the hours of natural sunlight. The practice of DST came and went during the early 20th century, and observance varied widely. In the 1970s, during a global petroleum shortage brought on by an OPEC oil embargo, DST became a necessary economic tool to reduce dependence on high-priced oil by relying more on the natural resource of the sun’s light. Fast forward to today: With the innovation of smarter energy practices and work hours that know no boundaries, not every country utilizes DST.
We know the sun doesn’t change its output, so exactly why does the change in the amount of daylight occur? The Earth’s tilt is the primary reason behind the seasons. This tilt, in tandem with the Earth’s position around the sun, determines how much daylight each hemisphere receives. Essentially, the amount of energy from the sun doesn’t change, but our ability to experience it does.
Spring is the transitional season when the Earth changes from winter to summer, when the planet begins to lean towards the sun. Along those same lines, autumn is the transitional season between summer and winter, when the Earth begins the process of tilting away from the sun. This slow-changing tilt towards, or away, from the sun yields longer, or shorter, amounts of time in which a given hemisphere can receive sunlight. The special day during which the Earth receives its maximum amount of sunlight is known as the “Summer Solstice,” which occurs on June 21 in the Northern Hemisphere and on Dec. 22 in the Summer Hemisphere.
Moving the clock forward in the spring ultimately removes an hour of daylight as we approach spring and summer seasons, when we already get more sunlight. Conversely, moving the clock back an hour in November yields an additional hour of daylight, which becomes especially useful as we approach the fall and winter seasons when the amount of sunlight becomes less. At the expense of sounding like a financial planner, consider the loss of the hour in the spring, a short term investment strategy for the upcoming fall/winter season gain; save that sunlight for a “rainy” day!
Keep in mind, the closer people are positioned to the north or south poles, the more likely they are to utilize DST. So, if you don’t like the annual “give” or “take” activity that comes with this practice, it’s best avoided by moving closer to the tropics, where the length of day and night varies so little throughout the year there is no need to alter the clocks.
Jordanna Sheermohamed is president and lead meteorologist of Weather Forecast Solutions, a private weather-forecasting company (www.WeatherForecastSolutions.com). Comments are welcome below.