Let’s start with ice spikes. You’ve probably seen tons of icicles – but have you ever seen one that formed upside down? Ice spikes seem to defy gravity, growing upward from an icy surface. Sometimes they’re outdoors, like in a bird bath, but you’re most likely to see them on ice cubes in your freezer.

They may look impossible, but they’re a result of the quirky way that water freezes. Most liquids freeze from the bottom up – the cooler molecules are more densely packed, and sink as they start forming a solid. But water is weird. It actually becomes less dense and expands as it freezes, because of the way that water molecules arrange themselves in a crystalline structure and form hydrogen bonds. That’s why ice floats in your glass, and why a pool of water freezes from the top down.

When a crust of ice forms, the remaining liquid water doesn’t really have room to expand as it transitions into a solid state. And sometimes, like in an ice cube tray, it finds another way to expand. If there’s a tiny gap in the surface ice, the water underneath can be forced up through it and make a tiny frozen spike.

Misty, gloomy fog appears when a cloud of water droplets forms at ground level. But when the temperature plummets, you might experience a little something called freezing fog.

Tiny liquid water droplets suspended in the air don’t necessarily freeze at 0 degrees Celsius. For ice crystals to form easily, the water molecules need a bit of something solid that they can glom onto to get aligned and start crystallizing, which is called nucleation. Without that, water droplets can become supercooled, staying a liquid below 0 degrees Celsius.

But as soon as they touch a solid surface – BOOM. They instantly freeze. So freezing fog can coat all kinds of things in a layer of ice. It can be beautiful, making trees and grass appear to glitter. But – as you might guess – it can also make for some dangerous driving. That’s why, if you hear the words “freezing fog” in your forecast, it might be best to plan on a cozy night in.

If you hear a loud boom that rattles your windows on a very, very cold night, don’t be so quick to blame supersonic aircrafts or aliens. You might have just heard the sound of a frost quake, also known as a cryoseism.

When changing weather causes the temperature to drop fast enough, water that’s seeped into the soil can freeze rapidly and expand, causing a miniature explosion underground. The shifting, cracking earth is loud enough that it reminds some people of sonic booms that planes produce when they break the sound barrier.

Frost quakes are pretty rare outside the polar regions, but they’re not totally unheard of. The winter of 2014 was cold enough to cause quakes across the upper Midwest United States, producing booms loud enough to wake people up at night.

In 2003, a frost quake in Maine even caused a 20-meter crack to open up in someone’s basement floor. Despite their power, though, these quakes are usually pretty localized. Seismographs often don’t pick them up, and people just a mile or two away might not even notice them at all.

To see a frost flower on land, head to the woods the morning after the first hard freeze of fall. These fragile petals and curlicues of ice form when plant stems rupture in freezing weather, letting the moisture inside ooze out and freeze when it hits the cold air.

Some plants are more likely to form frost flowers than others, and several different plant species actually share the common name “frostweed” because of it. One thing all these plants have in common is that they’re all perennials, which means they have a root system that lives through the winter.

As water seeps out of the split stem tissue, more is drawn up from the roots thanks to capillary action, the same force that lets a sponge or paper towel soak up a spill. Water molecules tend to stick each other – which is called cohesion – and to surfaces around them – or adhesion. So they follow each other up the tiny channels inside the plant tissues, providing enough moisture to create these exquisite ribbons.

But you’ll need good timing to see these icy blossoms in action. Frost flowers are as short-lived as they are beautiful, melting as soon as the sunlight touches them.

The term frost flower can also refer to flower-like formations that appear on new, thin sea ice. Because that’s not confusing at all. It’s hard to get close enough to study them, because they form on such delicate ice.

For a long time, we assumed they were formed by freezing fog depositing ice crystals on the salty ocean surface. But the problem with that theory was that these frost flowers mostly formed when the air was dry.

It turns out that when the air is cold enough, water sublimates directly into vapor from the solid surface of the ice, skipping the liquid stage altogether. When this water vapor touches chunks of ice again, it refreezes thanks to nucleation, and can form flower-like structures. These delicate structures have an unusual characteristic for ice: they’re salty. Really salty.

As salt is pushed out of the sea ice forming below, the frost flowers wick it up into their crystals, becoming up to three times as salty as the ocean itself. When scientists from the University of Washington carefully collected and melted one of these salty sea ice flowers, they found that it contained less than two milliliters of water – but about one million bacteria. It’s such a cold, salty environment, that this is a major surprise. And researchers hope that frost flower bacteria may eventually give us clues about how microbes might survive in other extreme places – even outer space.

On rivers around the world, a strange sight might appear in winter: perfectly round circles of ice, rotating slowly in the current. These ice discs have been known to reach up to 100 meters across and last for months. In recent years, they’ve been seen in Canada, the US, and the UK. But they’re pretty rare, and there are multiple theories on how they form.

One main idea is that they form when ice freezes in a still patch in the middle of a swirling eddy. But a 2016 study also showed that ice discs will even start to spin under their own power, with no help from moving currents around them.

Scientists froze discs of ice in a Petri dish, and then floated them on the still surface of a water bath. And as the icy discs melted, they became a cold liquid water, and began to rotate. That’s because the cold water was more dense than the other water surrounding it, so it started to sink and created a vortex, spinning the disc on the surface.

Abraham Lake, a man-made lake at the base of the Canadian Rockies, is famous for photogenic bubbles that form in the ice every winter. But be careful – these bubbles can explode.

Bacteria living on the bottom of the lake decompose the dead organic matter down there for energy, and release methane gas that gets trapped as bubbles in the freezing water. If you poke a hole through the ice, you can light these bubbles on fire, and scientists have done just that to prove that they really do contain methane.

Methane is a powerful greenhouse gas, seeping out naturally from wetland habitats around the world. You can find methane bubbles in other lakes in cold places, but Abraham Lake has a higher concentration of them because it’s man-made. The dam that captures its water also traps a lot of plant debris that would otherwise be washed away, providing lots of yummy junk for bacteria to decompose. Thanks to these icy bubbles, Abraham Lake has become a popular tourist destination, with photographers seeking that sweet Instagram shot of what are basically bacteria farts. So, hey, road trip anyone?

Tsunamis are known for their power, sweeping away beachfront buildings, and you might have seen some grainy cell phone videos of slow-motion ice tsunamis doing the same thing. The technical term for this phenomenon is ice shoves, but if you’ve ever seen one of those walls of ice marching ashore from a lake on a cold winter day, you’ll see why they remind people of their liquid cousins.

In 2013, ice shoves got up to 9 meters high and damaged homes in Minnesota and Montana, grinding up the lake shores with a crackling sound. In Minnesota, the wall of ice made it almost 25 meters inland and stretched along 4 kilometers of shoreline.

Videos and photos of the 2013 ice shoves look surreal, but they actually have a simple explanation. Chunks of ice form on the surface of the lake, and as strong winds push them towards land, they break up into smaller fragments and pick up even more ice along the way. So ice shoves are literally just ice being shoved along, sometimes right onto land.

Even though they’ve been known to cause some nasty damage, at least there’s plenty of time to evacuate before an ice tsunami hits. Forget outrunning them – these menaces can easily be out-walked.

Even if you never experience a frost quake or stumble across a frost flower, it’s safe to say that ice is pretty amazing. If it didn’t float on top of liquid water, aquatic life probably couldn’t exist at all.

Fish and other organisms, especially the bottom-dwellers, wouldn’t have anywhere to escape. So it’s no fun to drive on, and we might get a little too much of it here in the Montana winters, but we shouldn’t take the power and beauty of water ice for granted.

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