All storms are powered by evaporating water, and hurricanes always form over oceans. That means they can be powered by miles and miles of warm ocean water that’s been heated up by the Sun. The more warm water there is, the more powerful they get. Hurricanes can build and build in strength until they run out of fuel - meaning, when they hit land!

Some would say snow is frozen rain, but that’s actually not quite right. If you took tiny water droplets and froze them, you would get little balls of ice, more like hail - not the intricate snowflakes we know and love. So what’s the difference?

Well, both snow and rain start out as water vapor high up in the air. That’s just water in gas form - invisible, just like most gasses are. In order to turn back into a liquid, it needs to be cold, but the water vapor also needs a surface to attach to. That surface usually comes in the form of tiny dust particles floating around in the upper atmosphere.

When water vapor comes into contact with these tiny particles, it clings to them and turns back into liquid, forming raindrops (this is called condensation). But if the air is cold enough, the water skips the liquid phase and turns straight into a solid (this is called deposition), freezing onto the dust particle. As the dust particle blows around, more and more particles of water freeze onto it, growing a snowflake that eventually becomes heavy enough to drift down. So long as all the air between the cloud and the ground is below freezing, it will stay frozen until it reaches the ground as snow!

The best snowball comes from the best snow, and the best snow has the perfect amount of moisture. See, snow can be classified by how much liquid water is in it. That water is what holds the snowball together, sort of like snowball glue. The ideal amount of water for snowballs is about 3-5%. To tell how much moisture your snow has, try squeezing it and seeing how much water comes out. If none comes out, your snow is too dry. If a lot comes out, it might be too wet, and won’t break apart when it hits someone. If just a little bit comes out, it’s probably perfect, which means it’s time for a snowball fight!

Clouds are giant particles of dust floating through the air with small amounts of water surrounding them, either in liquid form (for rainclouds) or in solid crystal form (for snow clouds). A lot of people think clouds are gaseous water - that’s not true! The water in clouds used to be gaseous, but turned into a liquid (or solid, in the case of snow clouds) upon contact with a tiny dust particle.

Fog is a cloud that touches the ground. It happens when it’s very, very humid - there has to be a LOT of water vapor in the air. There also needs to be dust or some kind of other air pollution that the water vapor can condense onto. Fog is basically the same phenomenon as mist, except fog is thicker. If you can see really far - more than a kilometer, or about ⅔ of a mile - you’re standing in mist. Otherwise, you’re standing in fog!

Thunder is the sound of air exploding outwards from a bolt of lightning. When lightning strikes, the electricity heats the surrounding air to around 48,632 F°, or 27,000 C° - almost five times as hot as the surface of the sun! When it gets that hot, the air blasts outwards, creating a shockwave of air, which your ears detect as thunder.

Because sound travels slower than light, you can measure the approximate distance of lightning by counting how many seconds pass between lightning and thunder. Every 5 seconds represents about one mile (or every 1 second represents about 300 meters).

The average temperature of Earth’s atmosphere is slowly rising year by year, a phenomenon called global warming, or climate change. It’s caused by the emission of “greenhouse gasses” by humans. Greenhouse gasses are specific pollutants - mostly carbon dioxide and methane - that allow heat from the Sun to pass through, but don’t let it back out. That means that as they build up in the atmosphere, less heat is being reflected back into space, remaining trapped on Earth instead.

Greenhouse gasses come mainly from the burning of coal, oil, and natural gas for energy. Deforestation makes climate change even worse, because plants remove carbon dioxide from the air. As the Earth becomes hotter, the climate, or the long-term pattern of weather, is becoming worse for humans. Without strong, global changes to combat it, global warming will cause huge problems over the course of the next several decades and change the face of the planet.

The Northern Lights are an example of something called an aurora, and the explanation is complicated. So buckle up!

Earth is a giant magnet, which is good, because the Sun is constantly firing out super-hot protons and electrons, heated up so much that they were torn apart from the atoms they used to be a part of. They move really fast: from 250 - 500 miles every second. If you’re wondering if that’s dangerous, the answer is yes! Luckily, those particles are electrically charged, so the Earth’s magnetic field neatly deflects them towards the North and South Poles, and most of them end up going around Earth completely. Most, but not all!

Near the North and South Poles, sometimes some of those particles get past Earth’s magnetic field and strike the atmosphere itself. When they hit the nitrogen and oxygen atoms in our atmosphere, the collision makes light.

So if you are lucky enough to witness an aurora, you’re seeing microscopic, blazingly-fast particles exploded out from the Sun colliding with the air in our upper atmosphere. Awesome!

In short: they look at the way things are now, and compare that to what happened when things were sort of like this in the past. If things were sort of like this in the past, then what happens next will probably be close to what happened next back then. Simple…right?

In long: Scientists who study the weather are called meteorologists, and they make predictions about the weather by gathering tons of data, like temperature, wind direction, and wind speed. This data comes from ships, airplanes, radar stations, weather balloons, and satellites. They use that data to make predictions about the weather using complex mathematical equations. Nowadays, they feed the data into supercomputers that model the weather. They can compare the current data to similar data in the past to make an educated guess about what will happen next.