Example sentences
jīn今tiān天tiān天qì气zěn怎me么yàng样？
How's the weather today?
tiān天qì气biàn变lěng冷le了。
The weather turned cold.
The story behind the character
天
大 is a person with arms spread. Add one stroke on top and you get 天. The space above a person's head. So it didn't start as "sky," it started as "the top of your head." Only later did it climb up to mean heaven.
气
Three strokes of rising vapor. Xu Shen wrote 气, 云气也: "cloud vapor." Side note: the traditional 氣 is actually a different character (it meant "to gift grain"); they got merged when characters were simplified.