For a fixed pressure gradient, how does the geostrophic wind at 60ºN compare to that at 30ºN?

For a fixed pressure gradient, how does the geostrophic wind at 60ºN compare to that at 30ºN?

• A. Equal to that at 30ºN
• B. About 0.58 times that at 30ºN
• C. About 1.5 times that at 30ºN
• D. About double that at 30ºN

Answer: (B)

The geostrophic wind is influenced by the Coriolis effect, which varies with latitude. At higher latitudes, such as 60ºN, the Coriolis force is stronger compared to lower latitudes such as 30ºN. Specifically, the Coriolis force is proportional to the sine of the latitude. At 30ºN, the sine is approximately 0.5, while at 60ºN, the sine is approximately 0.866. For a fixed pressure gradient, the geostrophic wind speed is inversely proportional to the strength of the Coriolis force. This means that as the Coriolis force increases (which it does as one moves towards the poles), the wind speed must decrease for a constant pressure gradient. Consequently, the geostrophic wind at 60ºN is less than that at 30ºN due to the stronger Coriolis effect. The factor of 0.58 reflects this relationship, indicating that the geostrophic wind at 60ºN is approximately 58% of that at 30ºN, demonstrating the effect of latitude on wind speed under constant pressure conditions.

The geostrophic wind is influenced by the Coriolis effect, which varies with latitude. At higher latitudes, such as 60ºN, the Coriolis force is stronger compared to lower latitudes such as 30ºN. Specifically, the Coriolis force is proportional to the sine of the latitude.

At 30ºN, the sine is approximately 0.5, while at 60ºN, the sine is approximately 0.866. For a fixed pressure gradient, the geostrophic wind speed is inversely proportional to the strength of the Coriolis force. This means that as the Coriolis force increases (which it does as one moves towards the poles), the wind speed must decrease for a constant pressure gradient.

Consequently, the geostrophic wind at 60ºN is less than that at 30ºN due to the stronger Coriolis effect. The factor of 0.58 reflects this relationship, indicating that the geostrophic wind at 60ºN is approximately 58% of that at 30ºN, demonstrating the effect of latitude on wind speed under constant pressure conditions.