A jet stream is a high-altitude, fast-moving wind current in the atmosphere that affects flight conditions for aircraft. Jet streams are formed by the difference in temperature between the polar regions and the equator, and they typically 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 found at high latitudes, usually between 30,000 and 40,000 feet, and is characterized by strong westerly winds that can reach speeds of up to 250 mph. The subtropical jet stream is found at lower latitudes and is characterized by weaker winds that flow from east to west.

Jet streams can have a significant impact on flight conditions, especially at high altitudes. For example, flying with the jet stream can reduce flight time and fuel consumption, while flying against the jet stream can increase flight time and fuel consumption. Jet streams can also cause turbulence and other weather-related hazards, making them a critical factor for flight planning and aircraft operations.

In aviation, the location and intensity of jet streams are carefully monitored and considered when planning and executing flights. Flight planners use meteorological data and weather forecasts to determine the position and strength of jet streams, and to plan the most efficient and safe flight path for each flight.

Overall, the jet stream is an important part of the global atmospheric system and plays a critical role in aviation, affecting flight conditions and requiring careful consideration and planning by flight planners and aviation professionals.