The word monsoon may conjure in your mind torrential rains. But monsoon actually comes from the Arabic mawsim—meaning not rain but season.

In the tropics, there are only two seasons, known as dry and wet monsoons. They’re brought about by equatorial winds that blow in each spring and fall—predictably enough that sailors have depended on them for centuries.

During wet monsoons, the winds bring rain in tropical places around the world, like India and Southeast Asia. But also in the subtropics—like the American Southwest, Central America, northern South America, and West Africa.

When humid monsoon winds meet highlands, like in the Tibetan plateau or the Himalayan foothills, the moist equatorial air rises and more water vapor condenses out to produce those famous torrential downpours.

The largest wet monsoon rains ever recorded happened in India in the summer of 1860, with over one thousandinches of rain.

Wet monsoons recharge many of the great rivers of the world, providing water for millions of people and their agriculture.

But they can also produce devastating floods and cropland erosion and bring water- and insect-borne diseases.

Dry monsoons provide a welcome relief from the rains but sometimes cause drought.

These hardships aside, the wet–dry monsoon cycle is essential to life in the tropics.

Gold is malleable, portable, nontoxic, beautiful and rare. Those qualities have made it an excellent currency over the centuries.

But there’s another metal with all those properties and more—and it’s much more valuable.

It’s called rhodium, part of the platinum group of metals. The name comes from the Greek rhodon, meaning rose, for the rosy color of rhodium compounds.

It’s abundant in other parts of the universe but vanishingly rare in Earth’s crust—just one part in 200 million. We mine 100 times more gold each year.

Eighty percent of the world’s rhodium comes from South Africa. And 80 percent of annual supply is consumed by the auto industry.

That’s because, like all metals in the platinum group, rhodium is an excellent catalyst: it controls and encourages chemical reactions.

In your car, that means it’s used in the catalytic converter.

Exhaust flows through a metal honeycomb lightly spattered with rhodium and other platinum group metals. They turn dangerous nitrogen oxides and carbon monoxide into nontoxic nitrogen gas, carbon dioxide and water vapor.

Rhodium’s catalytic properties are in demand in other industries too.

There’s even an experimental technology that uses solar energy to turn carbon dioxide and water into high energy fuels using rhodium as a catalyst.

The Andean Condor is a giant vulture that lives along South America’s west coast. It’s one of the heaviest flying birds in the world, weighing more than 30 pounds. Yet it can stay aloft for hours at a time.

How do condors do it? Efficiency!

The condor launches itself from a high peak or cliff, spreads its massive wings—the largest in surface area of any living bird—and soars.

It will then ride thermals, currents of hot air rising from the ground, scanning the land below for carrion to scavenge.

If the condor doesn’t find a meal, it soars on, transitioning from one thermal to the next. 

Scientists recently tracked one bird and found it could fly this way for five hours, covering more than a hundred miles, without flapping even once!

In fact, condors have been shown to flap their wings only one percent of their total flight time, with 75 percent of their energy expended just getting airborne.

Because takeoff is so energy intensive, the big birds must avoid unnecessary landings. Meaning they have to manage their flight path very carefully.

How can they navigate from one invisible rising air current to another? Perhaps they watch the behavior of other birds or have learned to read the landscape to look for terrain that could produce updrafts.

Scientists still don’t know; a mystery that perhaps one day we’ll be able to reveal on EarthDate.

At the bottom of one of Africa’s deepest lakes lies a secret that could put two million nearby residents in danger.

Lake Kivu sits along the East African Rift Valley, where the tectonic plates that bisect Africa pull apart.

Volcanoes leak natural carbon dioxide into the bottom of the lake, where the water pressure is high enough to dissolve and concentrate the gas in water.

If the water temperature changes, or the water column is overturned, the CO2 can suddenly turn to gas again and shoot to the surface.

One such event happened in Cameroon’s Lake Nyos, erupting 300 feet in the air and causing a tsunami that swamped lakeside villages. A concentrated CO2 cloud filled the lowlands around the lake, displacing oxygen and killings thousands of livestock and people.

In Lake Kivu, bacteria process the CO2 into methane, meaning there are huge volumes of both gases—2,000 times greater than in Lake Nyos.

To keep them from erupting in a potentially larger and more deadly event, scientists now pump the lake’s deep waters to the surface, where the methane evolves out.

It’s piped to shore and used as cooking fuel in place of wood to prevent deforestation and local air pollution and to make electricity for local communities.

The CO2 is pumped back to the bottom of the lake where it’s stored and monitored.

In this way, science and technology have turned Kivu’s gases into a beneficial energy resource.

Microscopes, telescopes and lenses. Smartphones, laptops and televisions. Mirrors, windshields and cathedral windows.

None would be possible without glass.

It’s made of silicon dioxide, or quartz, that’s melted and then cooled so fast that crystals can’t form, which gives glass its most important quality today: transparency.

But glass was first valued for the way it breaks. Early humans found naturally occurring glass— from volcanoes or when a meteor superheated desert sand—and used its broken shards to cut things or make weapons.

Not too much later, humans learned to melt sand to make glass. They added metal salts to make different colored glass for jewelry and to adorn metalwork. Soon, different cultures were blowing glass to make colored plates and vessels.

But it wasn’t until the industrial age that glass assumed today’s roles. Transparent, inert, sanitary, and weatherproof, glass made windowpanes, bottles and jars, chemical beakers and electrical insulators. Each year, its uses expanded.

Using complex manufacturing and exotic additives, modern glass can withstand bullets or atmospheric reentry; form supersharp microscopic blades; make fibers that can be woven into building insulation; and so much more.

Clearly, our lives would be pretty dull without glass.

Fireflies are sometimes called lighting bugs or glowworms. But they’re not flies, bugs or worms—they’re beetles, with a marvelous capability.

They move oxygen through a tube in their abdomen to combine it with a special pigment called luciferin to produce bioluminescence, the familiar glow that gives fireflies their name.

There are 2,000 species of firefly around the world and 170 in the US. Different species produce different colored light, from bright red to fluorescent green.

And they flash their light differently too.

Males of some species blink their own unique message, hovering a few feet in the air, signaling to females on the ground, who flash back. When the language is right, the male flies down to the female to mate.

In different species, the males synchronize their flashing, all sending the same message at the same time. It’s thought that this brighter light gives females a better look at their suitors.

Once mated, the females lay eggs. The larvae grow underground, then the immature beetles crawl around in leaf litter, eating worms and slugs, before they mature and take flight.

If you’d like to see fireflies around your house this summer, provide a good environment.

Don’t spray pesticides, which kill fireflies and other beneficial insects.

Allow the grass to grow longer and leave some leaf litter around trees.

Then keep your outside lighting low: a dark yard will invite fireflies to flash their unique language of love.

In 1836, Charles Darwin and his colleague Joseph Hooker visited Ascension Island, really just a barren pile of volcanic basalt topped by an old cinder cone, ironically named Green Mountain.

There were very few plants, but some soldiers had successfully grown a vegetable garden in the volcanic soil. This gave Hooker a crazy idea. He contacted his father, the director of the botanical garden in London, and persuaded him to send plants.

Hooker and Darwin believed that if they could establish a thriving plant colony on the island, it would trap water and self-perpetuate.

By 1850, the Royal Navy had brought dozens of species from Europe, Argentina and South Africa. Just 20 years later, Hooker and Darwin were proved correct. The plants thrived and still do today.

Near the coast there are now grasses, shrubs and mesquite. Higher up the slope, cactus and acacia trees grow in the increasing moisture.

Above 2000 feet, the island becomes a misty cloud forest of ferns, eucalyptus, bamboo and evergreens, with food crops like fruit trees, coffee and ginger.

A water catchment system built long ago is no longer needed since the island makes its own wet microclimate.

Green Mountain is now in fact green—a signal that similar efforts, in places with the right potential for rainfall, could regreen other barren landscapes—maybe even on other planets!

We’re all familiar with those violent shaking events we call earthquakes. But it may surprise you to know that Earth more often moves without quaking in what’s called a slow or silent slip. It sure surprised scientists: they discovered this just 20 years ago.

Earth’s tectonic plates began to move over a billion years ago. Their constant motion has formed, pulled apart, and slowly destroyed continents for millennia.

Each tectonic plate rotates around an axis, while its edges collide with, slide over, or subduct under other plates.

While some of this movement occurs in dramatic releases of stress that produce earthquakes, nearly as much energy is built up and released in slow motion—so slow it’s hard to measure.

Scientists found evidence of one slow-slip event that went on for 32 years around Sumatra, before it finally gave way catastrophically, in the tragic earthquake of 1861.

They discovered this by looking at old coral.

In times of rising sea level, corals grow upward, seeking sunlight.

In the waters around Sumatra, they found five times the coral growth rate over those three decades, revealing that the ocean floor beneath the reef was subsiding, as the Indo-Australian Plate slowly slipped beneath the Eurasian Plate.

Understanding slow-slip events like this may one day allow scientists to better predict the earthquakes that often follow them.

Scientists have a new way to measure rain, or rather, rain intensity.

They looked at data from 185 weather stations across the globe, from 1999 to 2014, to determine how much rain fell in how many days.

They found that, on average, one twelfth of an area’s rain falls in its single wettest day, one eighth in its wettest 2 days, and half in just 12 days.

They decided to standardize this metric—the number of days it takes for half the rain to fall—as a way to gauge rain intensity in an area.

This is important because it’s intense rain that overwhelms the soil‘s capacity to absorb water, or the ability of a drainage system—of storm sewers, creeks and rivers—to carry water away, leading to floods, landslides and other impacts.

Scientists then projected what a warming atmosphere might mean to rain intensity.

Since warmer air can hold more water vapor, we could see more rain overall. This might be good news for places that don’t get enough rain.

But in already rainy areas, the increased rainfall may occur within its highest intensity rain days. The single wettest day could see 20 percent more rainfall.

This could occur while population, and the cost of infrastructure, continue to rise in coastal cities around the world, putting more people at risk of flooding, with more need for better flood warning and management.

The South Pole is the most inhospitable place on Earth—yet, each year, around 50 brave scientists and staff endure the winter there. Outside temperatures approach minus 120 degrees Fahrenheit in constant darkness.

And they better hope nothing goes wrong. Because no one can come to help them.

The South Pole is 800 miles from the nearest human contact. That’s farther than the International Space Station, which orbits less than 400 miles above Earth.

From research bases on the Antarctic coast, it takes planes 5 to 8 hours to fly to the South Pole. But it’s so cold in winter that jet fuel turns to slush, meaning no flights can come or go.

An over-land caravan of snow tractors in the summer takes 40 days.

The sun is up in summer for more than 4,000 hours, one six-month-long day. At that time, the South Pole research station has its highest population, 200 scientists and staff. They study solar spots and atmospheric ozone, cosmic rays and neutrinos.

Low temperatures still average negative 20 degrees Fahrenheit.

In the fall, the sun nears the horizon for six weeks of dusk. Then it sets and is gone for three months for that seemingly endless night that is Antarctic winter.

It takes a special person to endure the isolation, darkness, danger and lethal cold.