SME
Grade 6 Science · Problem type
How high clouds form
Use this for “How high will the clouds form?” from the temperature and the dew point.
Diagram
Air temperature: 25 °C
Dew point: 17 °C.
Air temperature is 8 °C warmer than dew point.
Height of the cloud base: 1,000 m
This is an example. Type your own values to start a new problem.
Air temperature
example · °C
Dew point
example · °C
Temperature difference
calculated · °C
Height of the cloud base
calculated
Formulas
From 17 up to 25: 8
How far the air temperature is above the dew point = temperature difference
8 × 125 = 1,000
Temperature difference × 125 = height of the cloud base
Assumptions
•
The dew point is the temperature at which water vapor starts to condense into droplets.
•
Rising air cools, and clouds form where it has cooled to its dew point.
•
Each 1 °C between the air temperature and the dew point puts the cloud base about 125 m higher above the ground.
•
The air temperature is at least the dew point. A cloud base at 0 m is fog.
Step-by-step
WE KNOW
Air temperature: 25 °C
Dew point: 17 °C
FIND
temperature difference, height of the cloud base
Step 1 · Find temperature difference
From 17 up to 25: ?
How far the air temperature is above the dew point = temperature difference
Take the dew point from the air temperature.
Temperature difference = 25 − 17
Temperature difference = 8 °C
Step 2 · Find height of the cloud base
8 × 125 = ?
Temperature difference × 125 = height of the cloud base
Each degree of difference puts the cloud base 125 m higher.
Height of the cloud base = 1,000 m
Check
Put the numbers back in. Both sides should match.
From 17 up to 25: 8 ✓
8 × 125 = 1,000 ✓
Topic check
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