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

Station Day

Station Day: Shadow tracker
// Energy from the Sun, and why some places get more of it
⏱ about 20 min

Station Day: Shadow Tracker

Saturday at noon, Rocket plants a stick in the planter and marks the end of its shadow with a pebble.

"Same time every Saturday," he says. "If the shadow changes, the Sun's angle is changing."

Raven measures the shadow with the ruler. "What do you notice? Should it get longer or shorter over the next weeks?"

"Depends which way our half of the Earth is tilting," Rocket says. "Toward the Sun, shorter. Away, longer."

Nova records the length. "The National Weather Service uses this very test to show the seasons," she says.

"Keep the pebbles. In a month you will have a row of them, and a story."

  1. Energy from the Sun reaches the Earth by radiation, warms the surface, and warms the air by conduction and convection.
  2. Because the Earth is a sphere, the equator receives more energy per square meter than the poles.
  3. The axis is tilted by about 23 degrees. The tilt, not distance from the Sun, causes the seasons.
  4. Land warms and cools faster than water, so day-to-night swings are greater over land. That difference makes sea breezes.
  5. NASA's energy budget: about 29 percent reflected, 23 percent absorbed in the air, 48 percent absorbed by the surface.
◇ FAMILY SHADOW TRACKER
On a sunny day, push a stick upright into soil or a pot in a spot that gets midday Sun. This is your shadow stick.
At the same time each Saturday, mark the tip of its shadow with a pebble and measure the length with a ruler.
Each family member predicts: will next week's shadow be longer or shorter? Write the predictions in the log.
Over the coming weeks, compare. The National Weather Service explains that shadows are shorter when your hemisphere tilts toward the Sun.
Talk about it: what does a changing shadow tell you about the Sun's angle, and about the season?
Safety first
Never look at the Sun, not even for a moment. Watch the shadow on the ground, never the sky.
The stick stays in soil or a pot on the ground, a railing or a windowsill, never on a roof.
For a grown-up
The shadow test only needs a stick, a ruler and the same time each week. Help your student remember the time.
Ask: why is the Sun's angle different at the equator and the poles? Why do we have seasons?
STATION DAY CHECK
  • Read the question.
  • Tap your answer.
Your hemisphere is tilting toward the Sun over the next month. What happens to the noon shadow?
What causes the seasons?
Which warms faster in the same sunlight: soil or water?
Shadow trackerTrue or false?
The shadow should be measured at the same time each week.?
It is safe to glance at the Sun to check its position.?
A changing shadow length shows a changing Sun angle.?
WHY THIS EXERCISEA fair comparison across weeks needs the same time and the same stick, and never your eyes on the Sun.
On paper, sketch the shadow stick and its shadow today. Leave room to add next Saturday's shadow beside it.
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