re: For RL, thanks for the link.
"According to the laws of physics, if the temperature of the air, (that is in a open environment like the atmosphere) becomes warmer, then the density must decrease and the pressure also must decrease."
Every day the air temperature increases significantly as the sun rises and decreases significant after the sun sets.
One can easily have differences in temperature of over 30 C in a one 24 hour period. It is also quite possible to have the atmospheric pressure during these wide swings in temperature, remain fairly constant. And one can also have at these times not much wind in the region.