Jet Stream

A jet stream is a narrow, fast-moving, high-altitude air current that can reach speeds of over 400 km/h (250 mph). These high-speed winds flow in a west-to-east direction and are located in the upper atmosphere, typically at altitudes between 10 and 15 kilometers.  Jet streams are caused by differences in temperature and pressure between the equator and the poles, and they can have a significant impact on weather patterns.

Jetty

A jetty is a long, narrow structure that extends into a body of water, typically a river or an ocean, and is used to protect shorelines or to serve as a docking point for boats. Jetties are typically made of wood, concrete, or rock and can vary in length from a few meters to several kilometers.  They are often built perpendicular to the shore and are designed to deflect currents and waves away from the shoreline, preventing erosion and creating a calm harbor.

Joint

A joint is a crack or fissure in a rock formation that occurs when the rock is under stress. Joints can vary in size and shape and can be filled with mineral deposits or sediment.  They are important in geology because they can influence the way that rocks erode and weather, and they can also provide pathways for the movement of groundwater.  Joints can be found in many different types of rock formations, including sedimentary, igneous, and metamorphic rocks.

Junction

A junction is a point where two or more things come together, intersect, or connect. In topography, a junction can refer to the meeting point of two or more rivers or streams, where they merge and form a larger body of water.  Junctions can also refer to the intersection of two or more roads, railways, or trails, and they are often marked by signs or landmarks.  In geology, a junction can refer to the point where two different rock formations meet, such as where a sedimentary rock layer meets an igneous intrusion.