Upper-Air Dynamics – Rossby Waves and Jet Stream Geometry In mid-latitude wave patterns, the ridges of long waves (Rossby waves) correspond to sectors where the jet stream bows closest to the:

Introduction / Context:
The wavy path of the polar-front jet stream reflects planetary-scale Rossby waves. Identifying where ridges and troughs place the jet relative to latitude helps forecasters infer temperature advection, storm tracks, and surface weather outcomes.

Given Data / Assumptions:

• Ridges are northward (in the Northern Hemisphere) or poleward bulges of height/flow.
• Troughs are equatorward dips of the jet stream.
• The question asks where the jet is closest during ridges.

Concept / Approach:
A ridge is a poleward excursion of the mid-latitude westerlies and jet core, commonly associated with warmer, sinking air (anticyclonic curvature). A trough is an equatorward excursion (cyclonic curvature). Therefore, at ridges the jet stream bows closest to the poles, whereas at troughs it dips toward the equator.

Step-by-Step Solution:

Verification / Alternative check:
500-hPa height analyses show ridge axes displaced poleward with a northward-shifted jet maximum on the ridge’s poleward flank, supporting the concept operationally used in forecasting.

Why Other Options Are Wrong:

• Equator: Characteristic of troughs, not ridges.
• Prime meridian: A longitude reference, unrelated to ridge/jet latitude position.
• None of the above: Incorrect because “poles” is correct.

Common Pitfalls:
Reversing ridge and trough effects. Remember: ridge = warm/poleward; trough = cool/equatorward in the Northern Hemisphere (signs reverse seasonally in details but geometry holds).

Final Answer:
poles