The list of source regions are:
Continental Arctic (winter only) - cA, dry and very cold
Maritime Arctic - mA, humid and cold
Maritime Polar - mP, humid and mild
Maritime Tropical - mT, humid and warm
North America is home to the continental arctic (cA), maritime polar (mP), maritime tropical (mT), continental tropical (cT), and continental polar (cP) air masses. The largest influences on North America's weather are the polar and tropical air masses that travel over the continent. These air masses, which pass through North America most frequently, have an impact on temperature and humidity. Cold, dry air masses frequently dominate the central and eastern United States during the winter as chilly winds blow from the northwest Canadian prairies. In the summer, the warm southern winds bring hot, humid air to the eastern and central US, resulting in days with high humidity and oppressive heat.
To learn more about air mass: https://brainly.com/question/19626802
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