Final answer:
The four main types of air masses are Dsb, Dsa, Cfc, and Cfb.
Step-by-step explanation:
The four main types of air masses are Dsb (Warm-summer mediterranean continental), Dsa (Hot-summer mediterranean continental), Cfc (Subpolar oceanic), and Cfb (Oceanic).
The Dsb air mass is characterized by warm summers and Mediterranean climate conditions. The Dsa air mass is similar to Dsb but with hotter summers. The Cfc air mass is found in subpolar regions with cool summers and mild winters. The Cfb air mass is oceanic, typically with mild summers and cool winters.