Under normal conditions the temperature of the atmosphere...

Under normal conditions the temperature of the atmosphere decreases steadily with altitude to a height of about 12 km (tropopause), above which the temperature rises steadily (stratosphere) to about 50 km . (a) What causes the temperature rise in the stratosphere? (b) The warm stratosphere completely surrounds the earth, above the cooler tropopause, maintained as a permanent state. Explain. (c) Sound waves emitted by a plane in the tropopause region will travel to great distances at these altitudes, with intensity decreasing, approximately, only as $1 / R$. Explain

Under normal conditions the temperature of the atmosphere decreases steadily with altitude to a height of about 12 km (tropopause), above which the temperature rises steadily (stratosphere) to about 50 km .
(a) What causes the temperature rise in the stratosphere?
(b) The warm stratosphere completely surrounds the earth, above the cooler tropopause, maintained as a permanent state. Explain.
(c) Sound waves emitted by a plane in the tropopause region will travel to great distances at these altitudes, with intensity decreasing, approximately, only as $1 / R$. Explain

Key Concepts

Atmospheric Temperature Stratification

The Earth's atmosphere is divided into layers, each with its own thermal profile. In the lower layer (troposphere), temperature generally decreases with altitude due to the dominance of convection and radiative cooling, whereas in the layer above (stratosphere), temperature increases with altitude. This stratification is essential in understanding atmospheric dynamics and energy balance.

Absorption of Ultraviolet Radiation

The increase in temperature in the stratosphere is primarily due to the absorption of ultraviolet radiation by ozone molecules. When ozone absorbs UV radiation, it converts the energy into heat, leading to a warming of the surrounding air. This process is critical in creating a temperature inversion where warmer layers lie above cooler ones.

Temperature Inversion and Atmospheric Stability

A temperature inversion occurs when a region of warmer air sits atop a layer of cooler air, which is a defining characteristic of the stratosphere. This inversion contributes to the stability of the atmosphere by preventing vertical mixing. It creates a persistent and homogeneous warm layer that surrounds the Earth, influencing weather patterns and the distribution of atmospheric constituents.

Acoustic Wave Propagation in a Stratified Medium

Sound wave propagation in the atmosphere can be significantly affected by temperature gradients. In a layered atmosphere with a temperature inversion, sound waves may be refracted in such a way that they are guided over long distances with reduced geometric spreading. This 'atmospheric ducting' effect alters the typical inverse-square law decay of sound intensity, allowing sound to travel farther than under normal free-field conditions.

Transcript

Please give Ace some feedback