Questions

Africa - 54 countries

South America - 12 countries

Antarctica - 0 countries

Europe - 43 countries.

Hence, Antarctica continent has the least countries.

Database provides necessary means to achieve this abstraction. By structure of a database we mean the data types, relations, and constraints that should hold on the data.

The area in which two types of air masses meet is called Front. There are two types of fronts. They are 

1) Cold front

2) Warm front

When a cold air mass pushes a warm air mass, it is called as Cold front. Similarly, when a warm air mass pushes the cold air mass, it is called as warm front.

Most important weather phenomena occur in the layer of Thermosphere.

Most of the weather phenomenon occur in the layer of Troposphere.