Scientists have witnessed the birth of atmospheric ice clouds, creating ice cloud crystals in the laboratory and then taking images of the process – documenting the first steps of cloud formation. Researchers witnessed a process known as ice nucleation in unprecedented detail, taking time-lapse movies of the first few seconds of when a particle attracts water vapor, forming ice crystals that become the core of icy cirrus clouds the high, wispy clouds that act much like a blanket for our planet...
Atoms of all elements consist of a central nucleus surrounded by a "cloud" containing one or more electrons. We can think of these electrons as occupying a series of well-defined shells. The number of electrons in its outermost shells determines the behaviour of a particular element. Other factors, such as the total number of electron shells, also play a part in determining behaviour but it is the dominance of the outer electron configuration that underlies the periodic law and justifies the grouping of the elements into groups or families.
Every substance contains a certain amount of heat, even a relatively cold substance such as ice. The substance's molecules are in continual motion and, by this motion, possess kinetic energy which produces heat. The average kinetic energy of the molecules are measured by temperature. Cooling to the point at which molecular movement ceases completely should thus be possible. Scientists are very interested in this point, absolute zero, but it is in practice unattainable. At temperatures close to absolute zero some materials exhibit remarkable properties, such as superconductivity and superfluidity....
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