Which one of the following is the source region for the formation of air masses?

The correct answer is the Siberian Plain.

Key Points

• Source region: It is an extensive region of the earth's surface where large masses of air having uniform temperature and humidity conditions originate.
• The best source regions for air masses are large flat areas where air can be stagnant long enough to take on the characteristics of the surface below.
  • That's why Siberian Plain is the correct option because it has a cold, large and homogeneous mass of land.
• The main source regions are:
  • The high-pressure belts in the subtropics from where tropical air masses rise, and
  • Around the poles, where polar air masses rise.

Additional Information

• Tropical air masses origin regions (Warm air source):
  • Tropical Oceans - warm and moist,
  • Sahara Desert - warm and dry.
• Polar air masses origin region (Cold air source):
  • Arctic Ocean - cold and moist,
  • Southern Ocean - cold and moist,
  • Northern Canada - cold and dry,
  • Siberia - cold and dry.