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Nature

2,233 cards. Each one is a 40-second story with a five-minute read behind it. Page 19 of 38.

1081. Salt and cold drive an ocean conveyor whose oldest water takes 1,000 yearsDeep beneath the waves, a slow global current is powered not by wind but by differences in temperature and saltiness. Heavy, cold, salty water sinks near Greenland and Antarctica …
1082. Thrust faults shove older rock on top of younger rock, breaking geology's ruleNormally the oldest rock layers lie deepest. Thrust faults flip that order, pushing ancient strata up and over younger ones, sometimes for kilometres. Geologists in the Alps, Scot…
1083. An ordinary thunderstorm lives about an hour and a half in three actsMost thunderstorms are born, peak and die in roughly 90 minutes, each stage lasting around half an hour. Warm, moist air shoots upward, builds a cloud that can top 20 kilometres, …
1084. Spring tides have nothing to do with spring, and neap means powerlessTwice a month, when Sun, Moon and Earth line up, their pulls combine and tides swing to their extremes. Those are spring tides, named for water that leaps up, not for the season. …
1085. The widest tornado on record measured about 4.2 kilometres acrossMost tornadoes are about 80 metres wide, blow under 180 kilometres per hour and fizzle within a few kilometres. The extremes are staggering: winds above 480 kilometres per hour, a…
1086. The trade winds were named for paths, not commerce, and they fertilise the AmazonTrade once meant a track, and the trade winds were simply the steady routes across tropical oceans. Portuguese sailors learned to loop with them in the 15th century, shaping which…
1087. Volcanic eruptions 201.4 million years ago cleared the stage for dinosaursAt the end of the Triassic, colossal eruptions across what became the Atlantic pumped out carbon dioxide and mercury, heating the planet and souring the seas. Up to a third of mar…
1088. In the tropics, rain sorts the climates because temperature barely changesA tropical climate never has a month averaging below 18 °C, so seasons are defined not by cold but by rain. Köppen's system splits the tropics into three kinds using a single numb…
1089. The world's largest land biome is only about 12,000 years oldThe taiga, or boreal forest, blankets 17 million square kilometres across Canada, Alaska, Scandinavia and Siberia, more than a tenth of Earth's land. Yet in its present form it ap…
1090. The softest mineral on Earth ends up in plastics, paper, rice and potteryTalc sets the bottom of the Mohs hardness scale at 1, soft enough to scratch with a fingernail. That softness comes from sheets of atoms held together by feeble forces that slide …
1091. Sweden's spring starts only after seven straight days averaging above freezingWhen does spring begin? In Sweden, meteorologists wait until the daily average temperature stays above zero for seven days in a row, so the date can land anywhere from mid-Februar…
1092. The grassy steppe helped spread horses, wheels and Indo-European languagesStretching from Ukraine across Russia and Kazakhstan to the mountain ranges of western China, the Great Steppe is the largest grassland region on Earth. Its open plains played a m…
1093. Jupiter's Great Red Spot has been raging for at least 340 yearsEarth's storms last from about half a day to a little over a week. Jupiter's Great Red Spot, a swirling system bigger than our whole planet with winds beyond hurricane strength, h…
1094. Scotland's Pentland Firth might generate 10 gigawatts from tides aloneWater squeezed through a narrow strait moves with enormous force, and unlike wind or waves, tides arrive on a predictable schedule. Estimates suggest turbines in Scotland's Pentla…
1095. A 17th-century priest worked out the basic rules for reading rock layersIn 1669 Nicholas Steno, a Catholic priest, set down a principle that sounds obvious once said aloud: in undisturbed layers of rock, the oldest lie at the bottom. That law of super…
1096. Midsummer Day falls near the start of modern summer, not its middleEngland still calls 24 June Midsummer Day, which sounds odd when summer has barely begun. The name survives from an older reckoning in which summer ran from 9 May to 10 August, wi…
1097. New Zealand drained 90 percent of its wetlands in about 150 yearsFor centuries swamps were written off as worthless ground, good only for hunting and trapping, so people drained them. Nine tenths of New Zealand's wetland vanished within roughly…
1098. A giant earthquake can make the whole Earth ring like a bell for weeksThe biggest quakes do more than shake the ground. They set the entire planet vibrating in tones with periods of up to an hour, and that ringing can be detected for as long as a mo…
1099. The same Mediterranean scrub goes by garrigue, phrygana, tomillares or bathaLow, soft-leaved scrub rings the Mediterranean, and every shore has its own word for it: garrigue in France, phrygana in Greece, tomillares in Spain, batha in Israel. Shrubland is…
1100. Light from the horizon crosses up to 38 times more air than overheadWhy is the sky deep blue straight up but pale near the horizon? Light arriving from low angles has pushed through as much as 38 times more atmosphere than light from directly abov…
1101. The phrase clean slate comes from pub tabs chalked on stoneInnkeepers once kept customers' charges on small framed sheets of slate, written in chalk and wiped when the debt was paid. That habit gave English the clean slate and the blank s…
1102. Snow is made of clear ice, so why does it look white?Each snow crystal is transparent ice, yet a snowfield glows white. The reason is scattering: countless facets, hollows and flaws bounce every colour of light around until it all c…
1103. A single gram of soil can hold billions of organisms from thousands of speciesScoop up a gram of ordinary soil and you are holding billions of living things, mostly microbes, belonging to thousands of species that science has barely explored. Soil packs rou…
1104. The world may already have passed peak phosphorus, back in 1989Phosphorus is the nutrient soils most often run short of, and plants cannot divide cells or grow seedlings without it. It comes from limited deposits of rock phosphate, and some e…
1105. In Sicily, weathering makes new soil at about a tenth of a millimetre yearlyUnder Sicily's Mediterranean climate, rock breaks down into fresh soil at roughly a tenth of a millimetre a year. At that pace, a hand's depth of earth represents many centuries o…
1106. China was sorting its soils into nine classes by the 5th century BCEThe oldest known soil classification appears in the Chinese text Yu Gong from the 5th century BCE, sorting land into three categories and nine classes by colour, texture and water…
1107. In Missouri a whole creek vanishes underground and reappears 9 miles awayAt Grand Gulf State Park in Missouri, an entire creek sinks into its own bed and disappears. The water travels underground and resurfaces about 9 miles off, helping feed Mammoth S…
1108. Frosted sand grains quietly reveal that the wind once carried themLook at a quartz grain under a scanning electron microscope and its surface tells a travel story. Polished grains and frosted ones have had different journeys, and a frosted finis…
1109. Nearly all the world's oil and every scrap of coal sit in sedimentary rockOver millions of years, sagging patches of Earth's crust fill with layer upon layer of sediment, sometimes almost 20 kilometres thick. These sedimentary basins hold virtually all …
1110. Sedimentary rock covers most land yet makes up just 8 percent of the crustWalk across the continents and nearly three quarters of the exposed ground is sedimentary rock. Dig down, though, and it turns out to be a thin skin: only about 8 percent of the c…
1111. Sapphires come in almost every colour except redBlue is only the famous version. Sapphire is corundum, crystallised aluminium oxide, and trace elements tint it yellow, green, purple, pink, orange, black or leave it clear. Red c…
1112. Some savannas pack in more trees per hectare than neighbouring rainforestPicture a savanna and you probably imagine lonely trees dotting a sea of grass. Yet Brazil's cerrado can hold 800 to 3,300 trees per hectare, matching or beating nearby tropical f…
1113. Schist gets its name from the Greek verb meaning to splitHeat and pressure during mountain building line up flat mica and chlorite crystals inside a rock until it peels apart into flakes thinner than a centimetre. That property, called …
1114. The Sargasso Sea has no coastline at all, only a ring of currentsMost seas are hemmed in by land, but the Sargasso Sea is bounded by nothing except the circling North Atlantic Gyre. Meanwhile the Sea of Galilee is actually a freshwater lake. Th…
1115. Sea ice is riddled with salty brine channels that host whole food websFrozen seawater covers about 7 percent of Earth's surface, yet it is far from solid. It is a mix of ice, trapped brine, air bubbles and salt, and those brine channels shelter micr…
1116. The ocean surface in one Indian Ocean spot dips 106 metres below averageSea level is not flat. Earth bulges at the equator and gravity varies from place to place, so the ocean's resting surface sags as much as 106 metres below the global mean in one I…
1117. Some of the mud on the ocean floor fell from outer spaceSeafloor sediment comes from four sources: eroded land, the shells of dead plankton, chemical reactions in seawater, and space. That last, cosmogenous material settles alongside t…
1118. A ship named Muirfield once struck an undersea mountain nobody had chartedMore than 14,500 seamounts, drowned volcanoes rising at least a kilometre off the seafloor, stud the oceans, and most have never been studied closely. In 1973 one gave its name to…
1119. Seasons come from Earth's tilt, and the warmest months lag the sunniestThe Northern Hemisphere gets its strongest sunshine in May, June and July, yet its hottest months are June, July and August. That seasonal lag is one surprise. Another is how many…
1120. Rainforests are not really Earth's lungs, but they may be its pharmacySomewhere between 40 and 75 percent of all living species may be native to rainforests, and more than a quarter of natural medicines were found there. Yet the popular idea that th…
1121. River rapids exist because hard rock refuses to wear down as fastRapids form where a riverbed tilts steeply and the rock beneath resists erosion better than the stretch downstream. Soft layers wash away, hard ones stay, and water tumbling over …
1122. About half of the world's rivers don't flow all year roundRivers seem permanent, yet roughly half of Earth's waterways stop flowing for part of the year, dried by desert seasons or locked in winter ice. Others keep running through drough…
1123. Deltas are named after a Greek letter because the Nile's looked like oneGreek writers saw that the land where the Nile meets the sea formed a triangle, like the capital letter delta. Herodotus used the name fourteen times for Egypt, but applying it to…
1124. The ocean floor is almost entirely one kind of rock: basaltAround 65 percent of Earth's crust by volume is igneous rock, born from cooled magma, and the oceanic crust is 99 percent basalt. Continents lean instead on granite and its relati…
1125. The famous Black Prince's Ruby in Britain's crown is not a rubyA ruby is simply red corundum, the same mineral as sapphire, coloured by a trace of chromium. Swap about one aluminium atom in a hundred and the crystal glows red, even fluorescin…
1126. Desert sand is plentiful, yet useless for making concreteConstruction consumes about fifty billion tons of beach and fossil sand every year, and on human timescales that sand does not come back. The world's deserts hold vast amounts, bu…
1127. Buried sandstone cements itself by dissolving the points where its grains touchUnder kilometres of sediment, sand grains press so hard against each other that the strained contact points dissolve. That dissolved mineral then settles into the open pores and g…
1128. Ancient thinkers believed quartz was ice frozen so hard it could never meltThe Greek word for crystal comes from their word for icy cold, because philosophers such as Theophrastus thought clear quartz was supercooled ice. Pliny the Elder agreed, noting i…
1129. Geologists nearly abolished the Quaternary, the period in which humans evolvedWe live in the Quaternary, the geological period covering the last 2.58 million years of ice ages and the whole span of recognisable humans. Yet not long ago the body that sets th…
1130. Raindrops are not teardrop-shaped; big ones look more like hamburger bunsChildren draw raindrops as teardrops, but real ones never take that shape. Small drops are round spheres. As they grow, air pressure flattens their undersides until the largest re…
1131. Newton gave the rainbow seven colours to match the notes of a musical scaleThe rainbow's seven colours are a choice, not a law of nature. Isaac Newton first counted five, then added orange and indigo so the spectrum would mirror the seven notes of a musi…
1132. The Phanerozoic, the eon of visible life, got its name from a mistakeGeologists named our current eon the Phanerozoic, Greek for visible life, because they once thought life itself began with it. They were wrong. Complex soft-bodied creatures flour…
1133. Plains cover over a third of Earth's land, and they even exist on MarsFlat land sounds like the least interesting landscape imaginable, yet plains blanket more than a third of the world's continents and feed much of humanity. They are built by river…
1134. The Tibetan Plateau is so high it helps steer India's monsoonAt about 5,000 metres above sea level and roughly 2.5 million square kilometres across, the Tibetan Plateau is the largest and highest tableland on Earth. It is still rising as tw…
1135. The polar vortex does not come to visit; its weakness lets Arctic air escapeWhen a brutal cold snap hits North America, headlines often blame the polar vortex. Scientists say that is not quite right. The vortex is a permanent ring of cold, spinning air ar…
1136. Dutch polders gave the country its oldest democracies and a style of politicsAround a fifth of the Netherlands was once under the sea. Keeping that reclaimed land dry demanded constant cooperation, and the water boards set up to manage it became the countr…
1137. Nobody agrees on where a pond ends and a lake beginsYou might think the difference between a pond and a lake is obvious, but scientists have never settled it. Definitions range from 2 hectares to 8, or rest on waves, light or roote…
1138. North America's tallgrass prairie was shaped for millennia by people setting firesThe prairie looks like untouched wilderness, but it was partly made by people. For 10,000 to 20,000 years, Indigenous peoples burned the tallgrass every year, and evidence suggest…
1139. The Precambrian covers 88 percent of Earth's history, and we know little about itNearly nine-tenths of our planet's story happened before the Cambrian, from Earth's birth about 4.6 billion years ago until hard-shelled animals appeared around 538.8 million year…
1140. Fog is not precipitation, but on Titan it rains methanePrecipitation means anything that condenses in a cloud and then falls because gravity wins. That rules out fog and mist, which simply hang in the air. Every year about 505,000 cub…

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