Teacher sheet · Ages 15–16 · about 45–50 minutes
Weather: pressure, wind and forecasting
Lesson page: echoesof.science/school/weather/ages-15-16/ · Pupil worksheet: echoesof.science/school/weather/ages-15-16/print/
Learning aims
- Use hPa, mb and Pa and explain why pressure falls with height.
- Explain wind as flow from high to low pressure, driven by uneven heating.
- Describe cloud formation and cold, warm and occluded fronts.
- Use the Beaufort scale with unit conversions; outline numerical weather prediction; evaluate a small data set.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: why do your ears pop in a lift or on a mountain road? |
| 15 min | Read the text; worked examples: force on 1 m², lightning distance, knots to mph. |
| 10 min | Read a real surface pressure chart: highs, lows and fronts. |
| 10 min | Set up the two-week pressure log; first readings. |
| 5 min | Quiz, or the Beaufort game as homework. |
Materials for the experiment
- A barometer, a digital weather station, or a phone with a pressure sensor (and a free barometer app)
- A rain gauge (home-made or school)
- A record sheet or spreadsheet
- Optional: the Met Office or national weather service surface pressure charts
Safety: Do not climb onto roofs or walls to place instruments. Stay indoors during thunderstorms; do not take readings while there is lightning.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Air pressure is the same everywhere. | It falls with height and changes from day to day as weather systems move. |
| Wind blows from low to high pressure. | Air moves from high to low pressure. |
| A forecast is a guess. | It is a calculation from millions of observations with physics equations, interpreted by forecasters; it is still uncertain because the observations cannot be perfect. |
Worksheet answers
- Low marked L; warm front: red line with semicircles; cold front: blue line with triangles; symbols on the side the front is moving towards.
- Area = π × (0.0635 m)² ≈ 0.0127 m²; volume = 0.0127 m² × 0.010 m ≈ 1.27 × 10⁻⁴ m³ ≈ 127 mL.
- A large pressure difference means a large force pushing the air from high to low pressure, so the air speeds up more and the wind is stronger; a small difference gives light winds.
- The difference (4 hPa) is bigger than the uncertainty in a single reading, so there may be a real link, but 12 readings over two weeks is a small sample from one place and one season. Stronger evidence: more readings over months, several locations, comparing with official data.
Quiz answers
- What is the force of standard sea-level air pressure on 1.0 m²? (1013 hPa) About 101 000 N. 1013 hPa = 101 300 Pa = 101 300 N on each square metre.[9]
- About what fraction of the air's molecules lie below 5.6 km? Half. Half of the atmosphere's molecules are within the first 5.6 km.[9]
- You see lightning and hear the thunder 9 s later. Roughly how far away is the storm? 3 km. Seconds ÷ 3 ≈ distance in km: 9 ÷ 3 = 3 km.[3]
- A wind of 36 knots is which Beaufort force? Force 8 (gale). Force 8 covers 34–40 knots.[12]
- At a cold front… cold dense air pushes under warmer air. Cold air is denser and pushes under the warm air.[10]
- What do supercomputers use as the starting conditions of a forecast? Millions of observations, blended by data assimilation. Observations from many instruments are assimilated into the model's starting state.[11]
Going further
Download a month of hourly pressure and rainfall data for your nearest official weather station from your national weather service. Plot both, mark the fronts from the archived charts, and test whether rain is more common when pressure is falling.
Sources used in this lesson
- [3] How do we measure the weather? (Met Office (UK national weather service)): reliability High
- [4] How we measure rainfall (Met Office (UK national weather service)): reliability High
- [5] Precipitation and the Water Cycle (U.S. Geological Survey (USGS), Water Science School): reliability High
- [6] Understanding weather (Met Office (UK national weather service)): reliability High
- [7] Why Does the Wind Blow? (NOAA / NASA SciJinks): reliability High
- [8] High and Low Pressure Systems (NOAA / NASA SciJinks): reliability High
- [9] Air Pressure (NOAA National Weather Service, JetStream): reliability High
- [10] Weather fronts (Met Office (UK national weather service)): reliability High
- [11] How weather forecasts are created (Met Office (UK national weather service)): reliability High
- [12] Beaufort wind force scale (Met Office (UK national weather service)): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/weather/sources/
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