pure water liquid −48.3 °C ice-forming nuclei

Pure water can stay liquid far below freezing

About −48.3 °C

Very pure water can remain liquid far below 0 °C if ice crystals have nowhere to start forming. Under carefully controlled conditions, liquid water can be supercooled to around −48 °C before it freezes spontaneously.

Homing pigeons can switch from the Sun to Earth's magnetic field

Homing pigeons normally use the Sun to help find direction, but they can switch to Earth's magnetic field when clouds hide it. If their magnetic sense is disturbed on an overcast day, they have trouble finding the correct direction.

The Wrights chose pilot control over stability

The Wright brothers designed their early powered aircraft to be unstable on its own. They believed mechanical controls would let a pilot correct for wind more effectively than built-in stability could.

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pure water liquid −48.3 °C ice-forming nuclei

Pure water can stay liquid far below freezing

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