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Each of the four seasons brings its own special events, like leaves changing color in autumn and the Aurora Borealis lighting up dark winter skies. But there are other surprising seasonal phenomena that exist in just one place. These four natural wonders occur only at a certain time of year, or even for a few fleeting hours, and their beauty and rarity have captured the imaginations of travelers.
Gruner See (Austria)
As anyone who lives near snowy mountains can tell you, local creeks and rivers swell every spring with a rush of snowmelt, the frigid waters from melting snowfields. That seasonal downhill flood feeds the white-water thrills of summer river rafting in places like Idaho and Colorado and, in alpine Austria, creates a summertime dive site from what is usually an above-water public park during the rest of the year.
Gruner See, a natural basin beneath the Hochschwab Mountains in the Styrian region of northern Austria, is normally just a 7-foot-deep, bright green lake in the middle of a public park — the kind of park with meandering pathways and lovely views of the surrounding dramatic landscape. Then, in May and June, melting snow fills the lake and everything around it, bringing the average depth up to almost 40 feet. Suddenly submerged in the clear alpine water, the grassy slopes and footbridges take on a surreal quality, like an Austrian Atlantis.
If you visit between May and early July, the water’s extraordinary clarity means you can see park benches, trees, and bushes under the water, even just standing on the shore of Gruner See. If you visit after the water recedes in July, you can walk park paths that were recently submerged and imagine the sights around you tinted an eerie green and silently waving around in the water. The local authorities, concerned for preservation of the pristine little park, banned swimming, snorkeling, and diving in 2016, but that doesn’t mean that visitors don’t show up to see the park, wet or dry, anyway.
Firefall (Yosemite National Park, California)
For a brief two weeks every February, as the evening sun sets in Yosemite National Park, its reddish-orange light illuminates the cascade of Horsetail Falls. The effect of the light catching the waterfall and its mist makes it look as though a stream of fire is falling down the rock face of El Capitan.
There’s no guarantee of catching Firefall, though, so witnessing the brilliant natural illumination is up to chance. While the exact angle of the sun can be predicted year to year, as can the time of sunset, the Firefall phenomena also depends on absolutely clear skies — even a wispy cloud can block the effect.
If you do chance a visit, you likely won’t be alone. Photographer Galen Rowell brought the falling fire phenom to the attention of the public with a famous shot of Horsetail Falls in 1973, and social media has elevated the capture of a personal Firefall photo to bucket-list status. The February pilgrimage to Yosemite has grown annually, and the park staff now restricts parking and traffic so they can limit the number of people crowding the viewing area.
Caño Cristales (Colombia)
If you were asked to draw a river, you’d probably reach for a blue or green crayon, but if you were asked to draw Colombia’s Caño Cristales, or Crystal Channel, you’d need a full array of crayons. This 62-mile-long river in the Caño Canoas Parque Nacional Natural Serranía De La Macarena runs in rainbow colors for part of the year.
The national park, in a stunning mountain range near the Andes south of Bogota, offers visitors petroglyphs, hidden waterfalls, jaguars, anteaters, and spectacular orchids. But most plan to arrive between July and November to see the Caño Cristales when a blooming river weed turns its waters psychedelic. Over time, the fast moving river and its falls have carved pits into the rocks along its bed, creating a perfect environment for the Macarenia clavigera plant to thrive. During certain months, the plant erupts into brilliant blooms that give the river its nicknames “River of Five Colors” and “Liquid Rainbow.” The plant mostly blooms in reds, maroons, and dark pinks, but where there’s shade over the water, the blooms grow bright green and yellow and sometimes even blue.
Sailing Stones (Death Valley National Park, California)
If Death Valley’s name and history aren’t eerie enough, how about a bunch of boulders that mysteriously move across the flat desert floor each winter? The rocks, some of which are as heavy as 700 pounds, have tumbled down from the surrounding mountains and hills and are made of the same dolomite and syenite. But they don’t stay put where they fall. Sometimes, they are found as far as 1,500 feet away, leaving behind tracks in the dirt where they’ve “sailed” across the desert floor.
This corner of Death Valley, Racetrack Playa, is actually a dry lake bed. For years, the public speculated about how the rocks moved — or were moved. (In addition to wind and earthquakes, aliens, ghosts, and teenage pranksters were thought to be behind the geologic shift.) Finally, a group of scientists took time-lapse photos of Racetrack Playa between November 2013 and March 2014 (winter is the only time the stones move). In addition to the photographs, they documented the temperature, precipitation, wind, and seismic activity during that winter. For good measure, they also attached a GPS unit to the top of the boulders.
Though not 100% conclusive, their findings indicate that the boulders move only when conditions are exactly right — a windowpane-thin sheet of ice must form on the scant surface moisture of the lake bed, then a strong wind must ripple the surface of water around the ice sheet and float the slippery but strong ice (with the boulder on top) in the direction that the wind is blowing. When the desert sun heats up, it melts the ice and surface water, leaving the tracks of the movement between the old and new location but otherwise no trace of the process. The study even explained the phenomenon of faint tracks that appeared on the ground but had no rock at the end, something that park rangers had thought was caused by visitors walking off with lightweight rocks. In fact, the tracks are left by just the ice sheet dragging itself along the muddy lake bed and then melting away.