Pressure
Sea level pressure with isobars, highs and lows.
Pressure shows the air pressure at sea level, with isobars and the centres of highs and lows, like a weather chart.
How to read it
Section titled “How to read it”High pressure usually brings settled weather; low pressure brings fronts and showers. Isobars close together mean strong wind. The lines are smoothed on purpose, so the large-scale pattern shows and small bumps do not read as false highs or lows.