Question

A relationship exists between the orientation of height contours and wind direction on 500-mb maps, especially at higher wind speeds. As seen in Figure 2 across the Washington State to Idaho area of the U.S., wind directions are generally ________ to nearby height contour lines. This is because the frictional forces acting on moving air at and near Earth's surface diminish rapidly with height and are essentially absent in determining middle and upper atmosphere motions.

a) Parallel
b) Perpendicular
c) Tangential
d) Oblique

Answer 1

Wind directions on 500-mb maps in areas such as Washington State to Idaho are generally a. parallel to nearby height contour lines due to the diminished impact of frictional forces at that altitude, resulting in a geostrophic wind flow.

Step-by-step explanation:

The student's question pertains to the relationship between the orientation of height contours on 500-mb maps - a type of atmospheric pressure map used in meteorology - and the universal wind direction at that pressure level in the atmosphere. In the example provided across the Washington State to Idaho area of the U.S., the wind directions are generally parallel to the nearby height contour lines.

This parallel relationship is typical in the mid and upper levels of the atmosphere because frictional forces, which can alter wind direction and speed near Earth's surface, have less of an effect as altitude increases. Therefore, in the absence of significant frictional forces, the geostrophic balance dominates and winds tend to blow parallel to isobars or contour lines, which represent areas of equal atmospheric pressure or height.