Lesson 12 of 14
The big picture
Show on a big screenPressure is force per unit area. Air moves from high pressure to low pressure.
| Idea | Remember | Example |
|---|---|---|
| Force over area | Pressure = force ÷ area. Unit: pascal. | A sharp knife |
| Liquids press too | Taller column, more pressure. Width does not matter. | A roof tank |
| The air presses | Air has weight. It presses in every direction. | A balloon |
| Why nobody feels it | Equal pressures on both sides balance. | You, and a sucker |
| High to low | Air moves from high pressure to low pressure. | Two balloons |
| Warmth starts wind | Warm air rises. Cooler air moves in. | A hot road |
| Breezes | Near the ground, wind blows to the warmer side. | Sea breeze by day |
| Cyclones | Rising warm moist air spins into a cyclone. | A calm eye |
| Fast air | Fast-moving air has lower pressure than still air beside it. The higher pressure pushes things towards the fast air. | Two balloons |
| Lightning | Lightning is a sudden flow of charge. It heats the air, and the hot air makes thunder. | Go indoors |
Read Chapter 6, Pressure, Winds, Storms, and Cyclones, in your NCERT book. Check each answer with high pressure and low pressure.