Middle latitude swirls are storm systems that transport humid warm air poleward to be replaced by colder and drier polar air moving equatorward. storm motions transfer within the earth system.

Warm atmospheric water vapour

Explanation:

As the middle latitudes on Earth lie between 23°26 and 66°33" north, and between 23°26' and 66°33" south. These are middle latitudes tropical cyclones or storms that cause swirls that transport humidity and warm air polewards to be replaced by the colder and drier air moving equatorward.  Anticyclone winds rotate clockwise in the Northern Hemisphere around a center of high pressure. They may be caused by the polar winds coming down and in return warm wind collision going up i.e a type of air front produced over water. Anti Trades and westerlies are found in this latitude. Their wavelengths may extend to 4000 kilometers and are generally slow-moving from east to west, with earth's rotational speed.

The answer i think is d