Tina is waiting at the bus stop. she sees and hears an ambulance as it approaches and passes by her. which two changes in the loudness of the siren does tina hear?

When ambulance approaches her, the loudness increases and when it passes by, the loudness decreases.

Explanation:

Loudness of the wave is determined by the amplitude of the wave. More the amplitude, louder will be the sound and vice-versa.

As, the ambulances reaches Tina who is standing at the bus stop, the amplitude of the sound increases which increases the loudness.

And when the ambulance passes by, the amplitude of the wave starts to fade away and the loudness of the sound decreases.

These two changes were experiences by Tina when she heard the loudness of the siren.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

conduction, convection, radiation