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Shortly after sunrise, an airfield situated along a coastline with the sea to the south in the northern hemisphere registers a surface wind of 350/06. The coastline near the airfield is aligned in an east/west direction.
Assuming anticyclonic conditions, the surface wind is likely to...

  • A

    Increase from the north by mid-morning before calming down in the evening.

  • B

    Become southerly to south-easterly and velocity decreases by afternoon.

  • C

    Become southerly to south-westerly and velocity increases by afternoon.

  • D

    Back to north-westerly and strengthen by mid-afternoon.

Refer to figure.
Early after sunrise, the wind typically represents a residual land breeze from the overnight period, flowing from the land towards the sea (northerly wind). As morning progresses and the sun rises, the land warms up faster than the sea due to its lower heat capacity, resulting in a temperature contrast between the two surfaces. This temperature gradient triggers the formation of a sea breeze, blowing from the cooler sea towards the warmer land. Consequently, the wind direction is expected to shift to a southerly direction.

As the day advances towards afternoon and the sea breeze gains strength, the surface wind is likely to veer, or shift clockwise, from its initial southerly direction to become south-westerly. This change is influenced by the Coriolis force.

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