← Back to course
Weather Lab 6-8 / Week 03 / Station Day
6/6
Week 03 · Air Has Weight

Station Day

Station Day: Barometer watch
// Air pressure, the barometer, and what rising and falling mean
⏱ about 20 min

Station Day: Barometer Watch

Saturday morning, the whole crew gathers around the jar. The straw tip is higher than yesterday.

"Rising," Rocket announces. "And look, the clouds are breaking up."

Raven checks the rain gauge: a little water from last night. "The low came and went. What do you notice now?"

"Lighter wind. Brighter sky. Rising glass," Rocket says. "A high is on the way. Probably."

Nova compares the card with the official report and glows. "Your marks and the data agree again."

"Three instruments, one story," Raven says, and writes it down.

  1. Air is made of molecules and has weight. Air pressure is the weight of all the air above a place.
  2. Standard sea level pressure is 1013.25 millibars, or 29.92 inches of mercury. Pressure drops as you go up.
  3. A barometer measures atmospheric pressure. Your jar barometer is a simple aneroid barometer that shows the trend.
  4. A low (red L) usually brings clouds, precipitation and moderate winds. A high (blue H) usually brings clearer skies.
  5. Read the trend: falling toward a low, rising toward a high, and state forecasts as chances.
◇ FAMILY BAROMETER WATCH
Gather the family at the jar barometer at the same time each day this week. Take turns marking the straw and the date.
Each person says the trend out loud: rising, falling or steady. Then each person looks outside and names one sign in the sky.
Together, write a one-line family forecast for tomorrow with a chance in it, such as "rain likely" or "fair, probably".
The next day, check the forecast. Keep a tally of hits and misses on the index card.
At the end of the week, talk about it: was the barometer a useful clue? When did it mislead you?
Safety first
The barometer stays indoors, away from direct sun and heaters, on a shelf or windowsill, never on a roof or ladder.
Never go outside to take a reading during a thunderstorm, flood or high wind.
For a grown-up
The jar shows change, not an exact value. Comparing with the official pressure for your area, from weather.gov in words, is a good check.
Ask your student: what does a barometer measure, and what does a falling barometer often come before?
STATION DAY CHECK
  • Read the question.
  • Tap your answer.
The straw tip is higher than yesterday. What is the pressure doing?
Rising pressure and clearing skies most likely point toward what?
Why does the family forecast include a chance, such as "likely"?
Barometer watchTrue or false?
Marking the straw at the same time each day makes the marks easier to compare.?
A jar barometer gives an exact pressure in millibars.?
A falling barometer often comes before clouds and precipitation.?
WHY THIS EXERCISEA family that reads the trend together will spot patterns faster than one person alone.
On paper, sketch the three instruments at your station: the rain gauge, the wind flag and the jar barometer. Label each.
← Friday