Friday, December 01, 2023

Earth just recently had its shortest day in modern history

| August 8, 2022 1:07 AM

Since 2020, our planet has been recording a series of speed records as it recently had its shortest day in modern history. On June 29, 2022, the Earth completed its full one-day rotation in 1.59 milliseconds less than 24 hours.

This recent measurement shows the Earth had its shortest day since the invention of atomic clocks. These highly-sensitive clocks measure time by monitoring the frequency of radiation of atoms and are currently used for navigation with satellite networks and GPS systems.

These devices were first proposed as early as 1873 by Scottish physicist James Clerk Maxwell. The first accurate atomic clock was put together in the mid-1950s. In 1967, the atomic clock was used to redefine the standard units of time based on atomic frequencies.

The Earth’s spin does fluctuate on a day-to-day basis, primarily due to gravitational forces from the moon. Based on data from atomic clocks, our length of day has increased by an average of 1.7 milliseconds compared to a century ago. Historical astronomical records show that the Earth’s length of day has also increased about 2.3 milliseconds since the 8th century.

Scientists estimate that the age of our planet is about 4.5 billion years old. They have also determined that a full day was around 18 hours and 40 minutes approximately 1.4 billion years ago, according to an article from The Guardian. Based on the data, the Earth’s spin has been slowing down. Occasionally, we have been adding leap seconds to compensate as the last adjustment was on Dec. 31, 2016.

Since 2000, the overall trend for the Earth’s rotation has been getting slightly faster as the planet set a modern record in late June. On July 26, according to, we came close to breaking the record again with a length of day 1.50 milliseconds faster. Scientists are not certain why we’re seeing this new trend. It could be related to the climate, the layers of the Earth, the oceans or other factors. It may also be the result of the planet’s “wobble,” which is the “irregular movement of Earth’s geographical poles.”

If this trend continues, it’s possible that we will have to adjust the atomic clocks with a “negative leap second.” This would be the first time in history this kind of adjustment would be made and could create issues for sophisticated computer systems.

In terms of our local weather, after one of the coolest springs in history across the Inland Northwest, we recently experienced one of the hottest and driest periods as well. Since July 18, there hasn’t been any measurable rainfall in Coeur d’Alene. In fact, only 0.07 inches fell on that date. July of 2022 was a bit drier-than-normal as only 0.72 inches fell compared to the normal of 0.92 inches. Most of July’s rainfall fell in the first week as 0.21 inches was reported since July 8.

Our big heatwave began on July 20 and continued through Aug. 3. High temperatures during that period were at or above 90 degrees with four consecutive days of over 100 degrees. The hottest day was on July 30 with a blistering 103 degrees. July 29 and 31 reported highs of 102 degrees. The average high-temperature during the 14-day span was 95.9 degrees, compared to the normal highs in the mid-to-upper 80s.

At the Spokane International Airport, the last four days of July were over 100 degrees with highs of 102 degrees on July 29 and 31. It’s been very hot in Lewiston as the last seven days of July had highs at or above 100 degrees. The hottest day was on July 29 with a scorching 108-degree temperature.

As I mentioned last week, that two-week period will likely be the hottest and driest period of the summer season. We’ve already had 16 days with highs at or above 90 degrees with more expected this week. Once again, our weather will often flip from one extreme to the other in short order.

Unless we see a stray shower or a thunderstorm, conditions in Coeur d’Alene and the rest of the Inland Northwest are looking very dry for the next 10 days to two weeks. However, the long-range computer models are starting to show a few changes toward the end of the month with the increasing chance of showers or a thunderstorm. Aug. 27 is also the new moon lunar phase and we’ll often have a higher probability of some shower activity during that cycle. Stay tuned.

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