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What If? Lab What if every day had the same weather? Weather changes because the Sun heats some places more than others, and big bodies of warm or cold, wet or dry air keep moving around. Imagine a world where every day had the same weather: no need to check a forecast, but plants and animals that follow the seasons might be confused. Some places near the equator come surprisingly close.
What If? Lab What if weather forecasts were always right? NOAA said in 2025 that a five-day weather forecast is right about 90 percent of the time, but a ten-day forecast is right only about half the time. Why? Because tiny changes in the air can grow into big differences, an idea called the butterfly effect. Imagine forecasts that were never wrong, and discover the satellites, balloons and supercomputers that make today's forecasts so good.
What If? Lab What if fog never lifted? Fog is a cloud resting on the ground, made of tiny water droplets floating in the air. Most morning fog disappears as the Sun warms the ground. Imagine fog that never lifted: travel would be slower, but in some dry places people already use nets to catch drinking water from fog.
What If? Lab What if the Moon had air? The Moon has almost no air, so its sky is always black and it has no weather. Scientists have found that the Moon once had an atmosphere, billions of years ago, but it was lost to space or became part of the ground. Explore what air would change, and why small worlds lose theirs.
What If? Lab What if air had no weight? The air above you has weight, and that weight presses on everything at about 101,000 newtons on every square meter at sea level. That pressing pushes juice up a straw and holds a suction cup on a window. Imagine air with no weight and follow what would stop working.
What If? Lab What if it rained every day? Rain is wonderful: it waters plants and fills rivers. But what if it rained every day? Soil can only soak up so much, so more water would run into rivers. Some rainforests and mountain slopes get rain very often, and life there is built for it. Explore what daily rain would change.
What If? Lab What if there were no clouds? Clouds shade the ground by day, send heat back down at night and are where rain comes from. Imagine a sky with no clouds at all, and follow what might happen to hot days, cold nights, rain and even the colors of the sky.
What If? Lab What if we could see the wind? Wind is moving air, and air is invisible. So people watch what the wind moves: smoke, leaves, flags, clouds and kites. Scientists even make wind maps from satellite pictures. Imagine the wind suddenly becoming visible, and follow the swirls, maps and kites that might appear.
What If? Lab What if snow fell in the desert? A desert is a dry place, not always a hot one. Clear desert skies let heat escape at night, some deserts are icy cold, and snow has even dusted sand dunes in the Sahara. Explore what happens when snow falls in a desert, and how desert plants cope with the cold.
What If? Lab What if the Sun had no sunspots? Sunspots are darker, cooler patches on the Sun made by strong magnetic fields, and their numbers rise and fall about every 11 years. Imagine a Sun with none: what would happen to its light, to solar storms and to the auroras they bring? Once, for about 70 years, the real Sun came close.
What If? Lab What if a greenhouse got too hot? Plants grow best when it is warm, but not too warm. Heat up a model leaf from a comfortable 25 °C to a scorching 45 °C and watch two things change at once: the leaf makes sugar more slowly, and it burns sugar faster. At some point it burns more than it makes.
What If? Lab What if the wind stopped blowing? Wind is air rushing from places of high pressure to places of low pressure. It carries heat, water and weather around the world, lifts seeds to new homes and has pushed sailing ships across oceans. Imagine all the air going still, and follow what might change.
What If? Lab What if there were no satellites? Thousands of satellites quietly circle Earth every day. They watch the weather, help phones find where you are with GPS and carry TV signals and phone calls. Imagine a world without them, and discover how people found their way and forecast the weather before the first satellite launched in 1957.
What If? Lab What if a balloon floated very high? As a balloon floats higher, the air around it gets thinner and pushes on it less, so the gas inside spreads out and the balloon swells. In our model, a perfectly stretchy balloon launched at sea level is about 14 times its starting size by the time it reaches 20 kilometers.
What If? Lab What if hurricanes could be steered? Hurricanes are huge spinning storms that grow over warm ocean water. Nobody can steer or stop one today: a hurricane holds far more energy than people could ever push around. What people can do is forecast where it may go and get ready early. Imagine steering one, then see why forecasts are the real answer.
What If? Lab What if there were no ocean currents? Ocean currents are like rivers in the sea. They carry warm water away from the equator and cold water away from the poles, and some lift food-rich water up from the deep. Imagine them stopping: follow the Gulf Stream, warm and cold coasts, and the rich fishing waters fed by upwelling.
What If? Lab What if every snowflake were the same? Each snowflake grows as it falls through air that keeps changing in temperature and dampness, so no two take exactly the same path or end up exactly alike. Imagine a world where every snowflake were identical, and discover what that would take and what scientists would lose.
What If? Lab What if clouds were made of candyfloss? Puffy clouds look like giant balls of candyfloss (cotton candy), but they are really made of tiny water droplets or ice crystals, and the water in a big one weighs about as much as 100 big African elephants. Imagine clouds spun from sugar instead, and find out what real clouds are made of.
What If? Lab What if cold wind blew over a warm lake? In late fall and winter, the Great Lakes are often much warmer than the freezing air that often blows in from Canada. As cold wind crosses the open water, it picks up warmth and moisture, rises and builds narrow bands of clouds that can drop 2 to 3 inches of snow an hour, while a town a mile or two away stays sunny. This thought experiment follows the air across the lake.
What If? Lab What if auroras could be seen everywhere? Auroras glow when tiny particles from the Sun crash into the air high above Earth. Earth's magnetic field steers them toward the poles, so that is where auroras shine most. Imagine lights over the whole planet, find out what makes the colors, and see how people keep satellites safe in big solar storms.
What If? Lab What if solar panels received less sunlight? A solar panel turns sunlight into electricity, so the more sunshine reaches it, the more power it makes. In our model, one rooftop panel on a clear summer day makes about 310 watts at noon. When clouds let through only a quarter of the direct sunshine, it makes only a quarter as much. Then find out why real panels can do better than our model on cloudy days.
What If? Lab What if you played catch on a merry-go-round? Roll a ball straight across a spinning merry-go-round and, to the riders, it seems to curve away. Someone standing on the ground sees it go straight. The same trick, on our spinning Earth, bends winds and makes big storms swirl.
What If? Lab What if a mountain wore away? Even the tallest mountains are slowly broken apart by ice, rain, plant roots and wind, and the pieces are carried away by rivers and glaciers. Imagine following a mountain as it wears away: its rock might end up as sand on a beach, mud on a farm or new land at a river's mouth, while moving plates push other mountains up.
What If? Lab What if birds forgot how to build nests? Nests keep eggs and chicks safe from predators and the weather, and birds build them in amazing ways: from twigs, grass, mud, hair and even spider silk. Imagine every bird forgetting how to build one. Then meet the birds that already manage without, from cliff-ledge murres to emperor penguins.
What If? Lab What if you counted the seconds after lightning? You see lightning almost at once, but its thunder travels at the speed of sound, about 343 meters per second. The National Weather Service says thunder takes about 5 seconds to travel a mile, so counting the seconds tells you how far away the lightning was. In our model, thunder from 1,700 meters away arrives after about 5 seconds.