Carbon dioxide is an amazing gas which gives life to the planet....

Carbon dioxide is an amazing gas which gives life to the planet. It helps to regulate our temperatures and provides energy for plants during photosynthesis.
Without CO2 life would not exist. It is as important as oxygen yet it is only 0.38% of the atmosphere where oxygen is 21% .
Carbon dioxide trap heat and as the hot carbon dioxide gas rises, it expands and cools as all gases do.
Why does air get colder as it expands?
The Ideal Gas Law states pV = nRT, where P = The pressure of the gas in Pa, V = Volume of gas in m³, n = Number of moles of gas, R = A constant of about 8.314 and T = Temperature in K.

As a gas (like air) expands, the value of V increases and this has the effect of increasing T (The temperature). As the energy needed to increase it's temperature must be supplied from somewhere, the gas takes the energy from the surrounding system giving the effect of cooling. This is a principle used in refrigeration

Carbon dioxide is a cool gas
https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth's_atmosphere