Saturday, March 7, 1970, in Perry, Florida, more than half a century ago, the day in the sunshine of a small timber town was spoiled by dense cloud cover that obscured a long-awaited total solar eclipse that more than 25,000 people had come to see.
The long-term weather data showed there was a 70 percent chance of clear or partly cloudy skies, which was the main reason why so many were drawn to this community, which is normally populated by only about 8,000 residents.
On that damp and gloomy Saturday. scientists from all over the world stood in the clutter of their cameras and meters, shaking their heads and waiting in vain for even a brief glimpse of the eclipsed sun. As the moon's gigantic shadow fell in on schedule, an eerie afternoon darkness fell over the landscape, accompanied by croaking frogs and chirping insects.
Related: Total solar eclipse 2024: everything you need to know
Max Waldmeier (1912 - 2000) a Swiss astronomer and director of the Zurich Observatory, who had a special interest in the sun, had planned this trip to Perry with his scientific team for two years, mainly because of the statistically encouraging meteorological patterns. But after that the moon 's shadow had passed, Professor Waldmeier was almost in tears as he helped his colleagues dismantle their heavy equipment.
This melancholic story is in stark contrast to that of three amateur astronomers, who also came to Perry for the solar eclipse. But instead of staying under the gloomy skies, they quickly piled their gear into a rental car and drove 350 miles overnight to Poston, South Carolina, where they found a nearly cloud-free sky.
On the day of the eclipse, at noon, they placed their various instruments in a tobacco field, where they watched the southwestern sky change from gray to pink and then to violet-gray as the moon's shadow rushed in. They saw Baily's beads and the scarlet solar chromosphere. and the whitish solar corona, brighter than a full moon, as well as irregularities in the moon's dark edge against the brilliant corona. When totality ended, a yellow "diamond ring" signaled that the spectacular event was over. One of the three observers said, "It was the shortest three minutes of my life!"
So if you really want to see the upcoming total solar eclipse, the moral is simple:
"Stay mobile!"
More about this later.
If you can't see the eclipse in person, you can watch the total solar eclipse live here on Space.com. And stay up to date on all the action with our total solar eclipse 2024 live updates blog.
Related: How to look at the sun safely (and what to look out for)
Statistics: Danger!
One must always remember that long-term climatological statistics - however reliable - are not absolute.
In his 1973 novel, "Time Enough for Love," science fiction writer Robert A. Heinlein offered the following aphorism: "Climate is what we to expectthe weather is our thing to get! "
How true is this!
And what happened in Perry, Florida in 1970 is far from an isolated incident. It's certainly happened more than a few times with other eclipses over the years.
Another excellent example of this is the total solar eclipse of July 11, 1991. The Big Island of Hawaii was completely within the path of totality. Climatology dictated that when the northeasterly trade winds blew, the eastern (windward) side of the island would see heavy clouds and rain, while on the sheltered lee (west side) of the island the trade flows would blow down and dry out. Because the trade winds blow 95 percent of the time in July, clear skies were thought to be a given for the west side of Hawaii. Unfortunately, on the day of the eclipse, a tropical tropospheric trough ("TUTT") passed over the Big Island, bringing more clouds than sun and disappointing the tens of thousands of people who had come to Hawaii to view the eclipse.
Over the past few weeks I've spoken with many people who have made arrangements to witness the April 8 solar eclipse from Texas. Comments are usually along the lines of: "I chose Texas because it has an overwhelming chance of clear skies." In reality, however, the weather forecast from Texas to the Deep South appears marginal at best.
Climatological data indicate little difference, from the point of view of weather from Texas to Arkansas. In this area, the average cloud cover in April is consistently around 60-65 percent. On April 8, clear days occur in about 45-50 percent of the years for which data are available, and the chance of seeing the eclipsed sun at some point on April 8 is about 55-60 percent. Granted, these conditions are slightly better than those for the Northeastern United States, Ontario, Quebec, and Atlantic Canada, but surprisingly not that much better.
In short, the weather in April is extremely changeable and changeable, so at any location along the path of totality, there is some hope for very clear skies (or dense clouds) on the day of the eclipse.
Keys to success: Latest predictions, common sense and mobility
Truly reliable meteorological weather forecasts for the day of the solar eclipse are not possible more than about a week in advance. At midlatitudes, large daily deviations from normal often occur during late winter and early spring. We must also take into account the eclipse itself, because even if April 8 starts with completely normal cloud cover, this would not be normal at the time of totality, because of the approximately 75 minute interval in which the partial eclipse increases. During that interval, reduced solar heating will result in a cooling of the local atmosphere, accompanied by a decrease in cumuliform cloud cover and an increase in stratiform cloud cover, as has actually been observed in previous eclipses.
So if your observing location on the day of the eclipse has done that blue sky mixed with a scattered to broken layer of puffy cumulus clouds just before the onset of the eclipse, you may want to stay where you are because as the partial phases progress and the Sun diminishes to a thin crescent, the ambient air temperature will likely drop and that convective clouds - powered by warming sunlight - will disappear. Conversely, if the local atmosphere is somewhat humid or stuffy, low stratus clouds or even fog may develop as the air cools.
In view of such weather uncertainties, plans about where to observe must be kept flexible until the latest possible time before the solar eclipse, which (as was the case in 2017) takes place on a Monday.
Related: Solar eclipse 2024 weather forecast: Q&A with an expert
Straight away, NOAA's Weather Prediction Center provides increasingly reliable forecast products, allowing people to choose a location where the chance of cloudy skies is low. These can be supplemented with forecasts National Weather Service prediction offices located near and along the total path.
Next weekend it will be time to switch from FORE casting to NOW casting: the very latest meteorological data, including careful examination of satellite images And radar scans should be used to modify plans based solely on climatological data.
Eclipse hunters today have a huge advantage over those of just twenty years ago, as they can now use their smartphone screens to view satellite and radar images, as well as GPS data to help make last-minute trips on local roads. An excellent paper reference guide to expanding your digital data is the " Road atlas for the 2024 total solar eclipse " by retired NASA astrophysicist and avid eclipse chaser Fred Espenak. The Atlas contains an extensive series of 26 maps of the path of totality through Mexico, the US and Canada.
Finally . . . as we emphasized earlier. . . a mobile strategy gives you the best chance of witnessing this greatest celestial roadshow, because wherever you plan to be, staying mobile to avoid clouds will always increase your chances.
To those who intend to position themselves on the path of totality in the hope of experiencing the panoply of phenomena that accompany the magical exclamation "totality!" We wish everyone good luck and clear skies.
