present simple or would?

This sentence comes from Active Skills for Reading 3:

In most parts of the world, storm clouds would be greeted with a frown. But in India, it's said that when the monsoon rains come, a billion people smile.

Why has the writer used would and not present simple (i.e., are greeted)? Grammar books say we use present simple for general statements. Why isn't the present simple used here then?

As @Peter Shor says, we need the context of the subsequent sentence because it completes the contrast.

"would" is used in order to imply a conditional because, in some countries, storms are rare.

Paraphrase

"In most parts of the world, if storm clouds appeared, they would be greeted with a frown. But in India, it’s said that when the monsoon rains come, a billion people smile."

You need to look at the whole context. With the following line, it reads

In most parts of the world, storm clouds would be greeted with a frown. But in India, it’s said that when the monsoon rains come, a billion people smile.

By using would, the writer is contrasting the rest of the world with India. You should interpret it as something like

If we weren't in India, people would greet storm clouds with a frown, but in India, people greet the monsoon rains with a smile.

If the writer had used the simple present are greeted rather than the irrealis mood would be greeted, the sentence would still be grammatical and would mean essentially the same thing.