In architecture and spatial design, atmosphere refers to the sensorial qualities that a space emits. Atmosphere is an immediate form of physical perception, and is recognised through emotional sensibility. Architects and designers use the notion of atmosphere to argue that architecture and space is designed and built for people to use and experience. Peter Zumthor in his book Atmospheres constitutes architectural atmospheres as "this singular density and mood, this feeling of presence, well-being, harmony, beauty...under whose spell I experience what I otherwise would not experience in precisely this way".