system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does it feel warmer when the air is humid than when it's dry?
gpt
>Why does it feel warmer when the air is humid than when it's dry?  
  
Releasing sweat does not have any cooling effect whatsoever. It needs to **evaporate**. It cannot do that well or at all if the air is already near-saturated with water vapor. Your body will therefore have a harder time shedding its excess heat.  
  
The vast majority of body heat is lost in the form of evaporation energy. A liquid requires a certain threshold energy - enthalpy - to change into its gaseous form. That's where the body heat disappears.
While your body also loses heat by other means (heat radiation and simple heat transfer to surrounding materials), evaporation energy lost to sweat evaporation is usually orders of magnitude bigger.