The jet stream is a fast-flowing river of air high in the atmosphere, typically found about 5 to 7 miles above the Earth's surface. It plays a crucial role in weather patterns, influencing the movement of storms and temperature changes. The jet stream can shift and change direction, which affects how weather systems develop and move across different regions. These powerful winds are usually found at the boundaries between cold and warm air masses. For example, when warm air from the tropics meets cold air from the poles, the jet stream can become stronger, leading to more extreme weather events. Understanding the jet stream helps meteorologists predict weather and climate changes more accurately.