Observing clouds in four dimensions

While easily seen by people, the cotton-ball clouds (called shallow cumulus clouds) that drift overhead on partly cloudy days are hard for radars and many other instruments to observe and, therefore, hard to model and predict. ...

Atomic motion captured in 4-D for the first time

Everyday transitions from one state of matter to another—such as freezing, melting or evaporation—start with a process called "nucleation," in which tiny clusters of atoms or molecules (called "nuclei") begin to coalesce. ...

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