Bill Burton: And it's time for us to take a look at the Science Behind the Forecast as I am joined by WAVE 3 meteorologist Tawana Andrew. Good morning. Tawana.
Tawana Andrew: Good morning. Today's topic has to do with something that we've seen a lot of recently.
BB: Yes, and are still seeing because of the cold conditions. We're talking about snow and snowflakes in particular. Enlighten us.
TA: So snowflakes form when you have a cold water droplet freezing onto a particulate like dust or pollen as it floats through the atmosphere. And that is what creates the initial ice crystal. So as this ice crystal just falls through the sky, eventually water will deposit onto it. So that is what it's called, by the way, when water vapor turns to ice, it's deposition. If it's the other direction, it's sublimation. So put that in your water cooler facts for today. So yes, as that ice crystal falls through the sky, the water vapor will deposit onto it, growing the crystal and forming that snowflakes. Now, for a snowflake, the ice crystals are symmetrical because of the lattice structure formed along and between hydrogens bonds, so a little bit of chemistry involved in this as well. So as you have those bonds between hydrogen forming and really creating these ice crystals. That is what you get. That is why you get that hex... Hexagonal, words are hard for me today, hexagonal, six sided shape. So we're going to keep an eye on more of that snow in the forecast, so you can think about those hydrogen bonds as the snow is falling, So as the ice crystal continues to tumble through the cloud, the water vapor will continue to deposit more along its edges and its corners, and that is what's causing it to grow. So a snowflake can grow in two different ways, faceted growth and branched growth. With faceted growth, you have the water vapor depositing on the edges of the ice crystals and leaves the face or what's called the basil facet of the ice crystal smooth and during branched growth, the water vapor accumulates on the corners of the hexagonal ice crystal, and as those corners grow longer and farther, then there are more locations for the hydrogen molecules to bond, and this is what causes those cool branches on a snowflake to form. And a snowflake can switch back and forth, by the way, between faceted and branched growth as it goes through different environmental conditions. Temperature, humidity, very important as an ice crystal falls through the sky, because that is what determines its shape. So let's say temperatures are near five degrees Fahrenheit. So that's pretty cold. You'll end up with a plate like crystal. These are a little bit flatter. When you have temperatures closer to 23 degrees Fahrenheit, you end up with more needle like and sharper crystals on a snowflake. And since atmospheric conditions are not uniform, each snowflake takes a slightly different path throughout the sky, and this leads to slight variations in the crystals growth, and that is why, in majority of cases, that two snowflakes will not look alike. It can happen, but it's very, very, very, very rare for it to happen.
BB: The odds must be astronomical.
TA: Yes, the odds are not always in its favor.
BB: There is so much to take into account when you think of something as tiny as a snowflake. It's absolutely amazing, but now we understand all of it much better thanks to this edition of Science Behind the Forecast with WAVE 3 meteorologist Tawana Andrew. Thanks for the knowledge, Tawana.
TA: Of course.
This transcript was edited for clarity
