Spot on Science: A Weird Winter Wonderland?
Winter is full of weird phenomena, including thundersnow, frost quakes, ghost apples and more! Margaret shares a few of these oddities.
Class Discussion Questions:
1) Draw a diagram that shows how ghost apples are formed.
2) Compare and contrast frost quakes and earthquakes.
Read the Script:
[Margaret] You guys, winter can be kinda weird. Let me tell you why. I've got a couple of odd phenomena to share about this frosty time.
Starting with these ghost apples. No, they're not from Johnny Appleseed's haunted orchard. These guys form when freezing rain coats an apple. The apple inside can't freeze as fast as that rain. Instead, the apple turns to mush and slips right out of the bottom of the ice shell.
Andrew Sietsema in Michigan took these photos while pruning a frozen orchard. He said his favorite is when Jonagold apples turn to icy shells that he calls Jona-ghosts.
Okay, so those weren't very creepy ghosts. How about this steaming lake though? Kinda eerie. This phenomena is called sea smoke or steam fog. It happens when steam rises off a warm-ish body of water and into air that is cold and dry. This lets the steam condense into visible haze.
This video captured by ehjoe on Twitter is happening over the Great Lake of Ontario. It was minus 19 degrees in Toronto, Canada where he captured the video.
So if you thought those sights were weird, how about the sounds of winter? Listen to this. It's thunder snow. It takes pretty perfect conditions for it to happen. The air close to the earth has to be warm enough to rise up and create a thunderstorm but yet cold enough to create snow.
During these thunder snowstorms, the lightning appears brighter since it reflects off the falling snow. But also, the snow quiets the thunder. So you can only hear it if you're very close to a storm.
Cold weather can also cause other booming sounds in the form of frostquakes. This happens when the ground is saturated with water. If the temperature drops suddenly, the water will freeze and expand into ice. This expansion can cause soil and rock to crack causing the loud noise and some shaking. The scientific term for these frostquakes is cryoseisms. They, too, are pretty rare and occur mostly in states near the Great Lakes or in Canada.
So the next time you hear a thump in the winter night, rest assured, it might just be old man winter stretching out.