Fast wind, low pressure

The idea

High-speed winds are accompanied by reduced air pressure.

Blow between

Two balloons hang side by side, a little apart. You blow air between them.

What do the balloons do?

• Move towards each other
• Move away from each other
• Do not move

Blow between them

Press Next step to blow.

Fast means low

Between the balloons the air moves fast, and the air pressure is lower there. The air outside the balloons has a higher pressure, so it pushes them together. Blowing harder makes them move together faster. High-speed winds are accompanied by reduced air pressure.

High-speed winds are accompanied by reduced air pressure.

Notes

Fast wind, low pressure. The higher pressure around pushes things towards the fast air.

Check yourself

You blow air between two hanging balloons. They move …

Air moving at a high speed has a …

When high-speed wind blows over a house roof, the pressure above the roof is …

It is safer to keep doors and windows open in a storm with high-speed winds because this …

• away from each other. Blowing makes a low pressure between them, so the higher outside pressure pushes them together.
• towards each other — correct. Yes!
• up only. They move towards each other.
• higher pressure. High-speed winds are accompanied by reduced pressure.
• pressure that never changes. High-speed winds have a reduced pressure.
• lower pressure — correct. Yes!
• lower than the pressure below it — correct. Yes!
• higher than the pressure below. Fast wind lowers the pressure, so it is lower above the roof.
• zero. It is reduced but not zero. The pressure above is lower than below.
• makes the wind slower. It does not slow the wind. It reduces the pressure difference.
• reduces the pressure difference between inside the house and over the roof — correct. Yes!
• makes the roof heavier. The roof does not change. The pressure difference is reduced.