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# Finding the Dew Point

Media Type:
Video

Running Time: 2m 45s
Size: 7.6 MB

or

Source: Cyberchase: "Gone with the Fog"

### Collection Developed by:

Collection Credits

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With the help of Cyberspace's favorite weathercaster Stormy Gale, the CyberSquad learns how to make fog. Stormy Gale explains that as you cool down moist air you get fog, and if you warm up the air, the droplets evaporate back into the air and the fog goes away. The CyberSquad has to figure out how cold they have to make the air before fog will form. Using a can of water and a bucket of ice, Stormy Gale explains how to keep track of the temperature and how to use the dew point to predict when fog will appear.

## Alternate Media Available:

Transcript (Document)

## Supplemental Media Available:

Let's Dew It! (Document)

Frame/Focus

Here are some Frame, Focus and Follow-up suggestions for using this video in a math lesson.

What is Frame, Focus and Follow-up?

Frame: Have you ever noticed droplets of water forming on grass? Or on the outside of a cold soda can? This is called dew (or condensation, in the case of the can), and it forms when the dew point of the air is higher then the temperature on the surface of the grass or can. Have you ever heard a meteorologist talk about the dew point? The dew point is the temperature at which the air becomes saturated and dew forms.

Focus: Watch and take note of how Stormy Gale shows the kids how to find the dew point using a can of water and a bucket of ice.

• How does Stormy Gale explain what the dew point is?
• How do you find the dew point?
• What happens when you cool down moist air?
• What happens with you warm up moist air?
• How did the CyberSquad know that the dew point was 55 Cyberdegrees?

Transcript

STORMY GALE: So...lemme guess... you need a little help about fog!

JACKIE: Yes, please. We're trying to figure out how to make fog.

STORMY GALE: Well, looks to me like you've already discovered the recipe: take moist air and chill. I think I'll use that on my next weather report.

DIGIT: Hey, where's the fog going?!

STORMY GALE: As the air warms, the droplets evaporate back into the air.

DIGIT: Huh? Come again?

STORMY GALE: The droplets change to water vapor... the way they were before.

WIDER: The fog is totally gone now.

JACKIE: So if you cool down moist air, you get fog...? Warm up the air...the fog goes away...?

STORMY GALE: You got it!

MATT: Great! Now we know how to make fog! Back to the Northern Frontier.

INEZ: Wait! We know how to make fog – but we still don't know how cold we have to make the air before fog will form.

STORMY GALE: No problem. All you have to do is figure out the "dew point" – the temperature at which dew -- and fog -- forms.

DIGIT: Uhh...what's a "do" point? When ya "do" see fog?

STORMY GALE: Not that kind of "do"! D-E-W! Did you ever see water droplets on the grass really early in the morning?

DIGIT: Yeah...! That's dew??

STORMY GALE: That's dew. Fog and dew are made the same way. Like this...

STORMY GALE: Here's a little experiment for finding the dew point.

JACKIE: A can of water and a bucket of ice?

STORMY GALE: We're going to use the ice to cool down the can until we see water droplets - or dew - on the outside of the can.

JACKIE: Ohhh! Like when water droplets form on a glass with an icy, cold drink...

STORMY GALE: Exactly. As soon as we see the droplets, we read the temperature. That's the dew point – the temperature at which condensation forms on the can.

JACKIE: The temperature is at seventy-five cyberdegrees now. And there aren't any water droplets on the can.

STORMY GALE: So we know 75 degrees is too warm for fog to form.

INEZ: Should I add some ice?

MATT: It's working! The can's getting cold.

STORMY GALE: More ice.

MATT: Still no water droplets.

MATT: It's down to seventy cyberdegrees!

INEZ: Sixty-five and dropping!

DIGIT: Still no water droplets!

MATT: It's not cold enough yet!

INEZ: More ice coming!

JACKIE: Temperature's down to sixty!

MATT: Water droplets forming! What's the temp now, Jax?

JACKIE: Fifty-five!

JACKIE: That means the dew point is fifty-five cyberdegrees.

STORMY GALE: Gotta go - time for another weather report! You guys have all you need?

INEZ You bet. Thanks, Ms. Gale!

STORMY GALE: Anytime.

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