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Atmosphere …exploring climate science
Science Museum, London
This is the transcript of an animation voice-over in the Climate Science Info Zone
exhibit.
Title: Climate feedbacks: Temperature and humidity
Voice-over: Female
An initial change in the climate can trigger feedback effects which either increase or
reduce the initial change.
One feedback, caused by a rise in temperature, is an increase in humidity.
This is because warmer air is capable of containing more water vapour.
This works a bit like a steam room, which can support very high humidity because
the air is so hot. If the temperature drops the steam condenses into larger water
droplets.
These droplets are too heavy to float in the air, so they fall to the ground.
Adding more water vapour won’t make the room steamy again, because the air is no
longer warm enough to support high humidity.
The atmosphere works in much the same way – if temperature drops, some water
vapour condenses into larger droplets and falls to the ground as rain.
More evaporation won’t make it humid again.
But if temperature rises, so does humidity.
Water vapour is a greenhouse gas, so adding more of it to the atmosphere increases
the temperature further.
This is one of the strongest positive feedbacks in the climate system, approximately
doubling an initial change in temperature.
www.sciencemuseum.org.uk/ClimateChanging/ClimateScienceInfoZone/ExploringEa
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