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There is convection in the troposphere of the Earth due to a phenomenon called atmospheric inversion. The troposphere is different from the stratosphere because the air mixes more rapidly; one can describe the troposphere as “turbulent”. The turbulence is linked to the inversion effect, in which temperature decreases with altitude at a rate of about 6 degrees Celsius per kilometer. This uneven heating by the sun (for instance, tropospheric air at the equator is hotter than that at the globe) easily spawns convection currents, large patterns of winds which move moisture and heat around the Earth. The stratosphere, which is dynamically stable with a vertical stratification of warmer layers above and cooler layers closer to the Earth, does not experience turbulence or regular convection. Air cannot rise if the air above it is hotter, so the air is stagnant. The cooler, denser air of the troposphere is trapped between the warmer, less dense air of the stratosphere, ensuring that air between the two layers rarely mixes, and convection is never carried over.
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