What is the difference between "gloomy" and "dismal" ?

I can't "feel" any difference.

The dictionary says they're synonyms but it cites some specific uses:

Dismal can mean "poor" as in: It was a dismal performance.

Gloomy could refer to "dark" weather: It was a gloomy day.

Many dictionaries suggest that the words are synonymous, defining both as causing or showing gloom or depression. In that sense, they are interchangeable. However, gloomy can also mean pessimistic or without hope, e.g., a gloomy view on the future of humanity.

A person can be gloomy, meaning down in the dumps, but not dismal, unless he's a dismal failure, and he can't be a gloomy failure in quite the same way. A gloomy swamp is a dismal one, though, and a dismal swamp is gloomy. The two words collocate differently sometimes, and they sound somewhat different notes in the reader's mind. There is no such thing as a synonym.

Thank you all.