Final answer:
Jet streams are caused by the temperature difference between the equator and poles, and they develop in the upper troposphere, typically having speeds between 110 to 185 km/h. A white 'J' within a jet stream representation usually indicates a core of very fast-moving winds, known as a jet streak.
Step-by-step explanation:
What Causes Jet Streams?
Jet streams are caused by the temperature difference between the equator and the poles. This temperature gradient generates high-altitude, high-velocity winds due to the Earth's rotation and the Coriolis Effect. Different air masses with different temperatures and pressures meeting at these altitudes contribute to the formation of jet streams.
Development and Characteristics of Jet Streams
Jet streams typically develop in the upper troposphere between 7 and 16 kilometers (23,000 and 52,000 feet) above the Earth's surface. They can have speeds generally ranging from 110 to 185 kilometers per hour (68 to 115 miles per hour), but speeds over 400 kilometers per hour (250 miles per hour) have been recorded. The size of a jet stream can be quite vast, stretching thousands of kilometers in length, and can be between 100 and 200 kilometers (62 to 125 miles) wide.
Significance of a White 'J' Inside a Jet Stream
If you encounter a 'J' symbol that is white inside a jet stream representation, it typically indicates a core of particularly fast-moving winds within the jet stream itself. This could signal a jet streak, a segment within the jet stream where the wind speeds are significantly higher than in the surrounding areas.