Clouds travel at different heights and speeds, and in opposite directions. Clouds fly against the wind. The sky is red at sunrise. Yellow streaks are visible in the sky at sunset. Smoke descends instead of rising.
Fog comes from landward direction.
Fog settles down toward the ground. The sun looks blurry or hazy, or has a halo. Stars twinkle more than usual. Flowers are especially fragrant. Trees show the undersides of their leaves.