usages of singular and plural nouns

Question

When I was learning English, I came across the sentence below.

A typhoon is a tropical cyclone.

This usage of the singular noun doesn't fit me because there are no necessities to use singular or plural nouns explicitly to give general explanations in my language.

However, I can understand this.

Typhoons are tropical cyclones.

I think using plural nouns is more frequent than using singular nouns when explaining something general due to intuitiveness of considering and determining the whole group. Plural noun is a collective of components and it is easily combined with the concept of normalization therefore it is persuasive that plural nouns are used in general expressions.

My questions are, after all,

1. Is the usage of singular noun in normalized explanation a common expression?

2. If it is common, what is the diferrence between the case of using singular nouns and plural nouns to express a general expression?

I appreciate you watching my lengthy and poor post.

Answer 1

Both ways of giving an explanation are very common. In the context in which you use it, there is no difference in the meaning being conveyed, and both solutions are perfectly valid.

When using the indefinite article 'a' to describe or explain something, you are really using the noun that follows as an example of all such types of object. It is a typical example of all such objects in the world.

A cat is a type of animal with fur and sharp teeth.

Or, you can just as logically refer to all the cats in the world, as they all share the same characteristics.

Cats are a type of animal with fur and sharp teeth.

Just to confuse you more, sometimes people will use the definite article to talk about a class, group or species of thing too.

The wildcat is a rare feline found in remote parts of Europe.

In this case 'the wildcat' is referring to the entire wildcat species, and it means exactly the same as:

Wildcats are a rare feline found in remote parts of Europe.