It is important not to confuse IMC with IFR (instrument flight rules) â IMC describes the actual weather conditions, while IFR describes the rules under which the aircraft is flying. Aircraft can (and often do) fly IFR in clear weather, for operational reasons or when flying in airspace where flight under VFR is not permitted; indeed by far the majority of commercial flights are operated solely under IFR.
Norbert Rillieux. Norbert Rillieux (1806-1894) was the inventor of the multiple-effect vacuum evaporator, which revolutionized the processing of sugar. He gained recognition as one of the prime architects of the modern sugar industry.
The Maunder Minimum (also known as the prolonged sunspot minimum) is the name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time. It caused London's River Thames to freeze over, and 'frost fairs' became popular.