Chapter 3.4 Clouds

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 2

Hot air takes up more water vapour

The relationship between the temperature and the maximum quantity of water vapour.

The dew point is when the water vapour in the air condenses. (cloud)

If the weather is clear and there are no clouds, it cools down quickly at night. It is then very likely that the temperature will fall to below the dew point. This is why grass is often soaking wet with dew after a clear autumn night.

Convective flow: An airflow that is created by a localised temperature difference

Condensation level: The height at which the water vapour starts to condense out.

If it is                    during the day, the air absorbs large quantities of water vapour.

Cold

Warm 

Part of that water vapour condenses again at night because the air

Cools down

Rises

Sinks

Warms up

The                        that the water vapour starts to condense at is known as the dew point.

Air pressure 

Altitude

Temperature

The more water vapour the air contains, the                              the dew point will be.

Higher

Lower

Cumulus clouds start out as rising ‘bubbles’ of warm air.
When does the water vapour in one of these air bubbles start to condense out?

Why are you not able to see the bubble of warm air until then?

It’s common for the morning to start sunny and for it to stay sunny for a few hours.
Explain why the first clouds only appear later in the morning.

As the evening falls, the clear patches gradually expand and then the last clouds fade away quickly around sunset. Before most of the stars are even visible, the weather is clear again.

Explain why the clouds only disappear again towards the evening.

In the Netherlands, fog is often produced when the days are hot and the nights cold. It is always very hot during the day in desert areas and it cools down a great deal at night. But you never get fog there can you explain why?