English Sentence
The air is stifling.
How come this sentence doesn’t use estar to describe the state of the air?
The air is stifling.
How come this sentence doesn’t use estar to describe the state of the air?
Using es, as opposed to estar, suggests to me that the stifling quality of the air is permanent. For example, imagine a tourist from a cold, wet and windy country going on holiday to a hot, and humid country - the change in climate could be quite a shock to the system.
Subtle one, but the answer is usage. Natives will tend to say:
El aire està caliente, fresco.
El aire es puro, toxico, sofocante.
However, frequency analysis shows that they will tend to equally use, depending on context:
No hard rules, as you can see.
Similarly, Spaniards tend to say “El cielo es azul.”, even if it is only meant for the day.
That reminds me of my Spanish teacher telling me the subtle difference between “mis zapatos son nuevos” (intrinsic quality on the day of purchase) and "“mis zapatos estàn nuevos” (for as long as they look new on the following days, but now the notion that it won’t last is expressed!).