A(n) is a large parcel of the atmosphere, sometimes subcontinental in size, that may move over earth's surface as a distinct, relatively homogenous entity.

The answer is:  "air mass" .

        "An    air mass    is a large parcel of the atmosphere, sometimes subcontinental in size, that may move over earth's surface as a distinct, relatively homogenous entity."

Aregion is an area of land that has common features. these features can be natural, such as climate or landscape. they can also be artificial, such as language or religion. the xinjiang uyghur autonomous region, above, is an area of china inhabited by uyghurs, a muslim group with ethnic ties to turkish people.