Jet streams are fast-flowing air currents found high in the atmosphere, typically at altitudes of about 30,000 feet. They form at the boundaries between different air masses, such as warm and cold air, and can influence weather patterns. These streams can travel at speeds of over 200 miles per hour and generally flow from west to east. There are two main types of jet streams: the polar jet stream and the subtropical jet stream. The polar jet stream is located near the poles and is associated with colder weather, while the subtropical jet stream is found closer to the equator and can bring warmer air. Both play a crucial role in shaping global weather systems.