[Black hole (OP)]

When atmospheric gases gain energy and become more heated they expand and effectively become less dense  that allows them to ascend .

My question is does the emission frequency of the molecules change and/or vibrations ?

[evan_au]

There are two major forms of electromagnetic emission - black body radiation, and line spectrum.
- The spectrum of Black-body radiation is related to the temperature of the material (whether solid, liquid, gas or plasma). It has a very wide bandwidth. If a gas gets hotter or colder, the black body radiation will change; for gas in earth's atmosphere, this radiation is in the infra-red part of the spectrum. For plasma in the Sun, the radiation spans  visible light, UV and infra-red.
- The line spectrum is related to energy transitions within atoms. In gases, it tends to have a fairly narrow line width, with different energy transitions producing different lines. The center frequency does not change with temperature, but as a gas heats up, the width of the line would increase due to the Doppler shift from moving atoms. Some transitions are more likely at different temperatures.

PS: In the early days of spectroscopy, new lines were discovered in the Sun's spectrum that could not be found in the laboratory on Earth. These were interpreted as new elements; Helium was a previously-unknown element. However, other lines were found to be common elements like Iron, but with most of its electrons torn off in the extremely hot plasma of the Sun's corona.
See: https://en.wikipedia.org/wiki/Sunlight#Composition_and_power

[Bored chemist]

The vibrational frequencies are pretty much a property of an individual molecule and an individual molecule doesn't have a defined temperature.