S4.14.2 For the adult
Weather and air pressure
The radio says a low pressure area is coming. Why does that mean cloud and rain, and what does a high bring?
What this chapter teaches
Air pressure is the weight of the air above. In a low, air rises and cloud and rain form. In a high, air sinks and the sky clears. Isobars join equal pressures, close isobars mean strong wind, and a wind is named for where it comes from. The learner builds a rain gauge and a wind vane.
Three questions to ask
There is no one right wording. Listen for the idea.
- What does the air do in a low, and what weather does that bring?
- What does a west wind mean, and which way does the vane head point?
- How do you find how much water fell on a roof from the rain in mm?
After the chapter, the learner can
- Explain how high and low pressure bring different weather
- Build a rain gauge and a wind vane and keep records
What they copy into their notebook
Low: air rises, cloud and rain. High: air sinks, clear sky. Close isobars, strong wind. A west wind comes from the west. 1 mm of rain on 1 m² is 1 litre.