Discovery

• World War II pilots crossing the Pacific discovered the jet stream. This current of strong winds has been defined as upper atmosphere winds found at between six and nine miles from the Earth's surface and that reach speeds higher than 57 mph.
  
  

Location

• The jet stream follows the line where masses of hot and cold air meet. This is where there is the strongest contrast in surface temperatures. In the winter months, the jet stream is stronger, since the contrast between arctic and tropical air masses is more dramatic.
  
  

Speed

• The average speed of the jet stream at its core is about 92 mph. During the winter months, these winds increase due to the greater contrast in surface temperatures, sometimes reaching 300 mph or more.
  
  

Appearance

• The jet stream stretches around the globe and is thousands of miles long. In contrast, it is sometimes only a few hundreds miles in width and a mere three miles thick. Though the stream flows in a westerly to easterly direction, changes in temperature may cause it to dip north or south, creating a wave like appearance.
  
  

Meteorological Maps

• The jet stream is wider than is often pictured on meteorological maps. The line drawn on the maps usually only indicates the core of the jet stream which bears the strongest winds. An analogy would be a river, with the strongest current being in the middle.
  
  

Theories/Speculation

• Some scientists have visions of tapping the jet stream to provide a wind energy source. In a 2007 article for SFGate.com, Silicon Valley entrepreneur David Shepard states: "My opinion is that 15 years from now, it'll supply most of the power in the United States."