The Key Difference Between "Westerly Wave" and "Continental Air" lies in their nature and origin:

1.    Westerly Waves (Upper Air Westerlies)

           Definition: These are large-scale **troughs and ridges* in the mid-latitude *jet stream* (upper-level winds) that move from west to east.

           Formation: Caused by **Rossby waves* (planetary waves) due to Earth's rotation and temperature contrasts.

           Impact: They influence **weather systems*, bringing cyclones, rain, and storms.

           Location: Found in the **upper troposphere* (mid-latitudes).


2.    Continental Air Mass

           Definition: A **dry and cold* air mass that forms over large land areas (e.g., Siberia, Canada).

           Formation: Develops due to **lack of moisture* and intense cooling over continents.

           Impact: Brings **cold, dry weather* in winter (e.g., cold waves in North India).

           Location: Forms near the **surface* (not upper air like westerly waves).


Key Differences

Feature          Westerly Waves                    Continental Air

Type                 Upper-air wind pattern                  Surface air mass 

Movement           West to East                            Depends on pressure systems

Moisture        Can bring rain (if interacting with moisture)                                Dry

Temperature        Varies (depends on wave phase)                      Cold (in winter)

Formation            Due to jet stream dynamics               Due to land cooling


Summary

        *Westerly waves* are *upper-air wind patterns* that steer weather systems.

        *Continental air* is a *surface-level dry and cold air mass* originating over land.