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The Science Portal
, in the broadest sense of the term, refers to any system of knowledge attained by verifiable means. In a more restricted sense, science
refers to a system of acquiring knowledge based on empiricism
, and methodological naturalism
, as well as to the organized body of knowledge
humans have gained by such qualified research
Scientists maintain that scientific investigation must adhere to the scientific method, a rigorous process for properly developing and evaluating natural explanations for observable phenomena based on reliable empirical evidence and neutral, unbiased independent verification, and not on arguments from authority or popular preferences. Science therefore bypasses supernatural explanations; it instead only considers natural explanations that may be falsifiable.
Fields of science are distinguished as pure science or applied science. Pure science is principally involved with the discovery of new truths with little or no regard to their practical applications. Applied science is principally involved with the application of existing knowledge in new ways, including advances in technology.
is a system that uses radio
waves to determine and map the location, direction, and/or speed of both moving and fixed objects such as aircraft
, motor vehicles, weather formations and terrain. A transmitter
emits radio waves, which are reflected by the target and detected by a receiver, typically in the same location as the transmitter. Although the radio signal returned is usually very weak, radio signals can easily be amplified, so radar can detect objects at ranges where other emissions, such as sound
or visible light, would be too weak to detect. Radar is used in many contexts, including meteorological
detection of precipitation
, air traffic control
detection of speeding traffic
, and by the military.
The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. This acronym of American origin replaced the previously used British abbreviation RDF (Radio Direction Finding). The term has since entered the English language as a standard word, radar, losing the capitalization in the process.
Lightning is a powerful natural electrostatic discharge produced during a thunderstorm. This abrupt electric discharge is accompanied by the emission of visible light and other forms of electromagnetic radiation. The electric current passing through the discharge channels heat rapidly and expands the air into plasma, producing acoustic shock waves (thunder) in the atmosphere.
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