kurai uchi ni okite sanpo o suru to, asa no kuuki ga totemo kimochiii desu.

If I get up and take a walk while it’s still dark, the morning air feels really pleasant.

Breakdown of kurai uchi ni okite sanpo o suru to, asa no kuuki ga totemo kimochiii desu.

• です: to be
• が: subject particle
• の: possessive case particle
• 朝あさ: morning

Questions & Answers about kurai uchi ni okite sanpo o suru to, asa no kuuki ga totemo kimochiii desu.

What does 暗い うち に mean here, and is it different from 暗いうちに written as one chunk?

暗い うち に is really the grammar pattern 暗い＋うちに → 暗いうちに and means:

• “while it is still dark / before it stops being dark.”

Grammar-wise:

• [plain form] + うちに = “while … is still the case / before that situation changes”
  • verb (dictionary form): 雨が降っているうちに – while it is still raining
  • i-adjective: 若いうちに – while you are still young
  • na-adjective + な: 元気なうちに – while (you are) still energetic
  • noun + の: 学生のうちに – while (you are) a student

So 暗いうちに focuses on doing something before it stops being dark (i.e., before sunrise), not just “at some random time when it’s dark.” It implies “while it’s still dark / before it gets light.”

The spaces in the sentence are just word-separators; you should read it as one grammar chunk: 暗いうちに.

How is うちに different from とき (as in 暗いとき)? Could I say 暗いときに起きて… instead?