The electromagnetic spectrum is the range of all possible electromagnetic radiation.
Above infrared in frequency comes visible light. This is the range in which the sun and stars similar to it emit most of their radiation. Nearly all objects in the universe emit, reflect and/or transmit some light.
(One hypothetical exception may be dark matter.) The distribution of this light along the electromagnetic spectrum (called the spectrum of the object) is determined by the object's composition.The composition of the atmosphere varies, depending on your location, the weather, and many other things. There may be more water in the air after a rainstorm, or near the ocean. Volcanoes can put large amounts of dust particles high into the atmosphere. Pollution can add different gases or dust and soot.
You have rated this answer /10