"stagnant atmosphere" is a perfectly correct and usable phrase in written English.
It is often used to describe a place or situation that is dull, lifeless or oppressive. For example, you could say, "The office had a stagnant atmosphere, with no conversation and no movement."
The laminar flow resulting from impingement of two steadily fed low-Mach-number gaseous jets issuing into a stagnant atmosphere from coaxial cylindrical ducts at moderately large Reynolds numbers, often used in combustion experiments, is studied through numerical integrations of the Navier Stokes equations.
The fuel jet emerges into a stagnant air atmosphere at temperature T0, with a velocity that varies periodically in time with non-dimensional frequency ωl and amplitude A = 0.5.
Stagnant air encourages disease.
"Talent-wise on paper, that is one of the greatest teams assembled, but the atmosphere was stale and stagnant.
Some geologists hold that the conditions were produced at depth by a stable stratification of lighter, fresher water overlying and sealing off from the atmosphere a more saline, stagnant layer.
Increased confidence and a sense of agency may account for the shift in unit atmosphere from apathetic and stagnant to one of enthusiasm and possibility that was reported by staff across several units.
But for all Mr Vavi's talk of reform, the atmosphere at the congress struck me as rather stagnant - at least on day one - preoccupied with narrow internal politics and external finger pointing.
The atmosphere surrounding the jets is of slow-moving (here taken as stagnant) combustion products, as is normal in a furnace.
The latter process causes mass loss of ice to the atmosphere, exposure of ice-enclosed meteorites, and flow of ice to the stagnant ice fields from adjacent regions to make up the mass loss.
