(aircraft humming) (gentle music) Oh.

(burner hissing) We are here at the Flying Circus Hot Air Balloon Festival and Air Show in Bealeton, Virginia, where I am going to be conducting a science experiment where I'm the subject, and we're talking about density.

Are you ready?

'Cause I'm ready.

Let's go, baby, whoo!

High flying fun just ahead on "Spotlight Earth."

(upbeat music) More from the air show momentarily, but we're gonna move it into the studio for now to get the working concept down before coming back to see density in action.

Thanks, Jarrell.

Be careful up there.

While you're taking flight in Bealeton, we're here in the studio expounding on that concept, density.

We'll start with the basic formula.

Density equals mass over volume.

Let's measure the density of an object, this block.

We can figure out the mass of it by putting it on this balance to get a mass of 112 grams.

Now we're going to measure the volume of the wooden block by multiplying the length times the width times the height.

The length is three centimeters.

The width is three centimeters.

And the height is eight centimeters.

When we multiply those, we get a volume of 72 centimeters cubed.

Once we have that info, we then take the mass and divide it by the volume, getting 1.56 grams per centimeter cubed.

That's the density.

The density of substances is an important driver of many of the attributes of the Earth and its different environments.

Density differences in air create our wind, weather, and climate.

Density differences in water create our ocean currents.

And density differences (volcano roaring) in the molten magma inside our Earth create plate tectonics, earthquakes, and volcanoes, (cup rattling) and shapes our landscape.

In fact, the density of an object determines its gravitational pull and thus drives the patterns of the whole universe.

We can use physics and manipulate the density of air to defy the gravitational pull and get up above it all.

Jarrell has been exploring that idea at the air show.

Jarrell, how was the flight?

My trip up was great.

(burner hissing) (laughs) How sick.

Yeah!

(laughs) (airplane humming) Yes!

(burner hissing) Earlier, I got a chance to talk to the pilot about the science behind the journey.

(upbeat music) Hot air rises because it's less dense.

So the burners heat up the air inside, and that gives it lift.

Wow, I love the colors.

It's like a circus tent.

Right.

Man, how much space is in here?

This is 3,000 meters or approximately 105,000 cubic feet.

It takes that much hot air to lift- Whoa.

A four-passenger basket.

It's all made of 1.8-ounce polyester.

Okay.

It's got 2,200 yards here.

The same material as like a sail?

Well, it's similar.

Okay.

Except it has a coating on it.

Okay.

And the coating actually protects the fabric from the heat.

Oh, okay.

What a cool place to be.

Right.

You can like do cartwheels in here.

Right.

Do a flip.

It still amazes me at how big it is.

It's huge.

It's like a house.

Right, it's about 85 feet wide.

Yeah.

And about 85 feet tall.

This is valve you said?

Right, this is a parachute valve.

See, what happens is you pull this line, and you break the Velcro that tabs it into place.

Okay.

And it spins and turns and seals.

Oh.

The hot air keeps it tight.

Right.

Then when you wanna go down, you vent.

You open the vent line.

Release it.

Our trip we went on, you called it tree topping.

Right.

Yeah?

You scrape the top of the trees.

Right, you can fly this very accurately within a few feet.

Yeah?

Yeah.

Very incredible.

Most people don't understand that you can steer a hot air balloon.

I didn't know.

But you can.

We can tack on our mark.

Okay.

And take off upwind and go downwind, much like a river, you know?

Yeah, right.

We fly the rivers in the sky on the air.

I like that.

Yeah.

I like that.

(burner hissing) Why do you love flying balloons so much?

Because it's kind of a nature walk in the sky.

It's really kind of a magic carpet ride.

Super fun stuff, Mark.

Thanks again so much.

Thank you.

While I relive my mile-high memories, let's send it back to the studio where they have their own density demo ready to go.

Thanks, Jarrell.

Let's take a look at density differences in water.

This tank is filled with water that is 68 degrees.

I have a cup with hot water.

It is 132 degrees.

We've added some red dye to help identify it.

In the cup over here with blue dye is cold water, coming in at 40 degrees.

If I dump the blue water in, do you think it will sink, rise, or just mix into the water?

Let's see.

(upbeat music) Looks like it sank to the bottom.

And so what do you think will happen when I add the red hot water?

Let's find out.

(upbeat music continues) Looks like it's staying on top of the water.

Cold water is more dense.

It can hold more substances and gases than hot water because of its density.

This happens in our oceans, creating large ocean currents.

Water is warmed by the sun where it shines the strongest, at the equator.

Then with the help of the Coriolis effect, it moves north or south towards the poles and cools and sinks, then moves back towards the equator in a global conveyor belt.

In the Earth's crust, there's a section that is the Earth's mantle.

There, magma is heated by the outer core, and it cools as it moves towards the surface.

These huge convection cells move the thin crust, or lithosphere, around the surface of the Earth in a process called plate tectonics.

You may have experienced this phenomenon if you've ever felt an earthquake.

So, there you have it, density explained and demoed both in the lab and in the field.

Speaking of the field, let's head back to Bealeton, where Jarrell's gonna wrap things up.

Jarrell, you all good?

So good.

What an exciting day.

Hot air balloon rides, an air show, can all seem like magic, but they're not.

It's science.

Thanks to my pilot, Mark, he showed me how everything has a specific or changing density, (burner hissing) moving things around in our environment.

(upbeat music) We're gonna leave you with more amazing images from the air show.

Thanks for watching.

See you next time on "Spotlight Earth."

(upbeat music continues) (upbeat music continues)