What causes cities like Denver to receive heavy snowfall during winter from warm, tropical air from the Gulf of Mexico?

The correct answer highlights the role of orographic lifting in causing heavy snowfall in cities like Denver when warm, tropical air from the Gulf of Mexico moves into the region. As this warm, moist air approaches the Rocky Mountains, it is forced to rise over the mountain range. This rising process cools the air as it ascends because temperature decreases with altitude. As the air cools, its ability to hold moisture diminishes, leading to condensation and precipitation in the form of snow.

This phenomenon is particularly significant in winter when the contrast between the warm, humid air from the Gulf of Mexico and the colder air typical of higher elevations is pronounced. The orographic effect is crucial in enhancing snowfall in these mountainous areas, particularly when the conditions allow for abundant moisture from the south.

Other options, while relevant to atmospheric processes, do not specifically address the interaction between warm, moist air and the topography that enhances snow formation in Denver.