Which air mass is described as very cold, very dry, and stable?

Which air mass is described as very cold, very dry, and stable?

• A. Continental Arctic (cA)
• B. Arctic
• C. Polar
• D. Tropical

Answer: (A)

The main idea is that air masses reflect where they form—temperature and moisture come from the source region. A very cold, very dry, and stable air mass comes from extremely cold, dry continental areas in the polar regions, which is the Continental Arctic. Its dryness comes from forming over land with little moisture available, and its extreme cold makes the air dense and resistant to vertical motion, leading to stable conditions (often with high pressure and clear skies). The other options don’t fit this exact combination: Arctic and polar air masses are cold, but not as dry or as stably layered as continental Arctic, while tropical air is warm and humid.

The main idea is that air masses reflect where they form—temperature and moisture come from the source region. A very cold, very dry, and stable air mass comes from extremely cold, dry continental areas in the polar regions, which is the Continental Arctic. Its dryness comes from forming over land with little moisture available, and its extreme cold makes the air dense and resistant to vertical motion, leading to stable conditions (often with high pressure and clear skies). The other options don’t fit this exact combination: Arctic and polar air masses are cold, but not as dry or as stably layered as continental Arctic, while tropical air is warm and humid.