あす vs あした vs みょうにち

I'm trying to understand the difference between あす, あした, and みょうにち.

I've read this page http://qweop.com/ug but I do not understand the last paragraph.

What does it mean that あした is used to refer to the "future" ? Isn't 未来 the "future" ?

Question

あす vs あした vs みょうにち

I'm trying to understand the difference between あす, あした, and みょうにち.

I've read this page http://qweop.com/ug but I do not understand the last paragraph.

What does it mean that あした is used to refer to the "future" ? Isn't 未来 the "future" ?

Answer

あしたis the most informal of these three. あすis less informal and has two meanings: tomorrow and near future.みょうにちis the most formal and used in business letters.

Answer

In the last paragraph, they talk about a metaphorical use of "tomorrow" to mean "future". It's the same as in English: "Nobody knows what tomorrow will bring" = Nobody knows what's going to happen in the (near) future.

Answer

あした」→「あす」→「みょうにち」の順に改まった表現になります。