Ten Natural Phenomena That Sound Made Up

In 2011, a camera crew for the BBC series Frozen Planet filmed something that looked like a special effect: a hollow tube of ice growing downward from the underside of Antarctic sea ice, reaching the seabed and then spreading across it like a frozen web, trapping sea stars and sea urchins in its path. Scientists call it a brinicle.

The physics is surprisingly tidy. When seawater freezes, the salt does not fit into the ice crystals, so it is squeezed out into pockets of very cold, very salty brine. That brine is denser than the surrounding seawater, so when it leaks out through cracks it sinks as a plume. Because it is colder than the normal freezing point of seawater, the ordinary water it touches freezes around it, building a fragile ice sheath that grows downward as the brine keeps flowing.

Brinicles have been known since the 1960s, and oceanographer Seelye Martin described the standard model for how they form in 1974. Researchers have since compared them to chemical gardens and to undersea hydrothermal vents working in reverse, and some have suggested that the brine channels inside sea ice could have offered chemical conditions useful to early life. The Frozen Planet footage was simply the first time anyone captured one forming on camera.

Imagine a single tube-shaped cloud stretching from horizon to horizon, rolling toward you at dawn like a giant rolling pin. That is the Morning Glory, a roll cloud that appears over the southern Gulf of Carpentaria in northern Australia with enough regularity that glider pilots travel to the small town of Burketown to ride it.

The clouds can be up to about 620 miles (1,000 kilometers) long and often sit only a few hundred feet above the ground. They can move at roughly 20 to 45 miles per hour. Roll clouds form elsewhere, but this is the only place where they can be predicted and seen on a regular basis.

According to Australia's Bureau of Meteorology, the trigger is the geography of the Cape York Peninsula. Sea breezes blowing in from the ocean on each side of the peninsula collide over land during the day. At night, cooler air descends and slides out over the gulf beneath a layer of temperature inversion, setting off a wave in the atmosphere. Moist air condenses into cloud at the rising front of the wave and evaporates at the back, so the cloud seems to roll as it travels. Meteorologists describe it as a solitary wave, a single pulse that can travel a long way without falling apart.

On certain nights, breaking waves light up electric blue. Every crash of surf sends a sheet of light racing along the beach, and footprints in the wet sand sparkle. It looks like a lighting effect at a theme park, but it is alive.

The light comes from dinoflagellates, single-celled plankton that drift near the surface. Some species are bioluminescent, and when they bloom in large numbers, the water can glow whenever something disturbs it. A wave, a boat hull or a swimmer's hand is enough. The light comes from a chemical reaction in which a compound called luciferin reacts with oxygen, often sped up by an enzyme called luciferase. The Smithsonian notes that the glow may work as a burglar alarm: a flash when a small predator attacks can draw the attention of a bigger predator that eats the attacker.

In Southern California, the best-known glowing displays come from blooms of a dinoflagellate called Lingulodinium polyedra, which also causes the reddish-brown water known as red tide during the day. The organism runs on a daily clock and glows most strongly at night, which makes it a favorite of scientists who study biological rhythms. Bioluminescence itself is everywhere in the ocean. NOAA estimates that roughly 80 percent of animals living between about 650 and 3,300 feet down can make their own light.

Photographs of erupting volcanoes sometimes show forks of lightning crackling through the ash cloud, as if a thunderstorm had been stuffed inside an explosion. The earliest written description comes from Pliny the Younger, who saw lightning in the dark cloud over Mount Vesuvius in AD 79.

The basic cause is the same as in a thunderstorm: electrical charges get separated until the air can no longer hold them apart and a spark jumps. The question has been where the charge comes from. Two studies published in 2016 in Geophysical Research Letters helped answer it. A team led by Alexa Van Eaton of the US Geological Survey studied the April 2015 eruption of Calbuco in Chile and found that in big eruptions, lightning followed the high, drifting ash plume, pointing to ice crystals forming in the cold upper cloud, just as in ordinary storms.

A second team, led by Corrado Cimarelli of Ludwig Maximilian University in Munich, recorded lightning at Sakurajima in Japan. There, sparks near the vent came from ash and rock fragments colliding and rubbing together, building up static charge with no ice needed. Shattering rock may also release charge right at the vent. So volcanic lightning comes in more than one kind, which helps explain why it can appear both low in the plume and high in the ash cloud.

Where the Catatumbo River empties into Lake Maracaibo in western Venezuela, thunderstorms build on so many nights a year that sailors once used them as a lighthouse. Locals call it the Beacon of Maracaibo. The lightning shows up in a 1597 poem by Lope de Vega and appears on the flag of the Venezuelan state of Zulia.

The numbers are startling. The Lake Maracaibo basin averages about 250 lightning flashes per square kilometer a year (roughly 650 per square mile), which Columbia University's International Research Institute for Climate and Society describes as the highest annual lightning rate anywhere on Earth. Estimates of how many nights it storms vary widely between sources, from about 140 to 260 a year, often for hours at a stretch.

The explanation is geography. The basin is hemmed in by the Andes and the Perijá Mountains. Warm, moist air from the Caribbean and the lake gets trapped and pushed upward when it meets the mountains and cooler air flowing down from them, building towering storm clouds night after night. A daily wind pattern called the Maracaibo Basin Low-Level Jet helps regulate the activity. An older idea that methane from swamps and oil fields fuels the storms is disputed, though some researchers think it may play a small role. The lightning can fade during droughts: in early 2010 it went quiet for weeks, setting off rumors it was gone for good, before returning.