Final answer:
Gap flows generally occur when the prevailing winds are perpendicular to mountain ranges, causing the wind to funnel through gaps and creating stronger wind flows that can lead to the rain shadow effect on the leeward side of mountains, resulting in arid conditions.
Step-by-step explanation:
Gap flows usually occur when the large-scale prevailing wind direction is perpendicular to a large mountain range. When this happens, the wind is funneled through valleys or gaps in the mountains, accelerating as it moves. This results in a wind flow that is stronger and can significantly affect climates and weather patterns on the leeward side of the range.
The moist air from the ocean that rises over a mountain range cools and condenses, leading to precipitation on the windward side. Rain shadow is the effect experienced on the leeward side, where the drier air descends, creating arid conditions. This phenomenon is essential to understanding the distribution of diverse climates around the world, such as the semi-arid conditions in eastern Washington and Oregon due to the Cascade Range.
Underlying east-west wind patterns are fundamental to the climate and can show patterns like those seen on giant planets such as Jupiter and Saturn, although scales and effects can differ substantially based on planetary characteristics and atmospheric properties.