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Weather Lab 6-8 / Week 02 / Monday
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Week 02 · The Sun Heats the Earth Unevenly

Monday

Sunlight is energy
// Energy from the Sun, and why some places get more of it
⏱ about 20 min

Monday: Sunlight Is Energy

Rocket slaps a hand on the dark roof tiles and yanks it back. "That is warm! The puddle next to it is cool."

Raven touches the metal railing, then the white planter, then the air above the tiles.

"What do you notice?" she asks. "The dark tile is warmest. The air above it feels warm too."

Nova hovers over the roof, scanning. "Everything up here was the same temperature at dawn," she says.

"One thing has been pouring energy onto this roof all morning. What is it?"

Rocket squints up, then quickly looks away. "The Sun. But why does it warm the tile more than the puddle?"

"Good question," Nova says. "Hold onto it until Wednesday's lab."

Rocket pulls his hand back from warm roof tiles while Raven touches a railing. Nova hovers above them in bright sunshine.

Where the energy comes from

The Sun generates energy. That energy travels through space to the Earth's atmosphere and surface.

Some of it warms the atmosphere and the surface as heat. That is how the National Weather Service describes the start of all weather energy.

NASA puts it simply: solar power drives Earth's climate. Energy from the Sun heats the surface, warms the atmosphere and powers ocean currents.

Every bit of weather you log at Station Rooftop starts with this energy.

Three ways heat moves

The National Weather Service describes three ways energy is transferred into and through the atmosphere.

WayWhat it meansWhere you see it
RadiationHeat energy travels through space as electromagnetic wavesSunlight warming the roof tiles
ConductionHeat energy passes from one substance to another, or within oneA warm tile warming the air touching it
ConvectionHeat energy moves in a fluid as the warm part risesWarm air rising off the roof

Radiation is how the Sun's energy crosses empty space. Infrared radiation is what produces the warm feeling on your skin.

Dark colored objects, such as asphalt, absorb radiant energy faster than light colored objects. They also radiate it away faster.

Air conducts heat poorly. So the air is mostly warmed from below, by the surface the Sun has heated.

As that warm air rises, it cools, and cooler, denser air moves in to replace it. We feel that moving air as wind.

CHECK THE THREE WAYS
  • Read the question.
  • Tap your answer.
How does the Sun's energy cross space to reach the Earth?
A warm tile warms the air touching it. Which way of moving heat is that?
Warm air rising off the roof is an example of which way?
Which absorbs radiant energy faster: a dark tile or a white planter?
StatementTrue or false?
The Sun is the source of the energy that drives Earth's weather and climate.?
Air conducts heat very well.?
Infrared radiation produces the warm feeling on your skin.?
As warm air rises, cooler and denser air moves in to replace it.?
WHY THIS EXERCISEThese four facts explain almost every temperature reading in your log.
Heat moving through space as waves is called ____.
Heat moving in a fluid as the warm part rises is called ____.
How many ways of transferring energy does the National Weather Service describe? Type a number.
Try it
In the shade, with a grown-up, lightly touch a dark surface and a light surface that have both been in the Sun.
Touch briefly, with the back of your hand. Which one held more of the Sun's energy?
Safety first
Never look at the Sun. Touch sun-warmed surfaces briefly, and never touch anything a grown-up says is too hot.
On paper, sketch the roof from the story. Add three arrows labelled radiation, conduction and convection where each one happens.

Strong start. Tomorrow you find out why the equator is warm and the poles are cold.