And, when atmospheric methane condenses, it makes fog.

当大气中的甲烷凝结就形成了雾。

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Be sure to dress warmly, it's usually quite windy on the top of Nob Hill and San Francisco evening fog makes it feel even colder.

旅行前要做好保暖工作，一般诺布山山顶风都特别大，旧金山晚上的雾也会使气候变得更冷。

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After a while, it becomes difficult to see how to move forward. And that just makes the fog even thicker.

因为这些发生后，会变得很难看到向前的方向。然后使得云雾得加浓重。

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