What does the expression “75 meters per second southeast” best describe?

Velocity because it has speed, along with direction.

Velocity is also a vector because it has both direction and magnitude.

Southeast is the direction of velocity while 75 m/s or instantaneous speed (meters per second) is the magnitude of velocity.

This is also equal to 270,000 meters an hour(m/h) or around 167.81 miles an hour(mph) or 270 kilometers an hour(km/h)

To convert seconds to seconds in an hour, multiply by 3600 because there are 60 seconds in a minute, and 60 minutes in an hour.

There are 1000 kilometers in an hour.

There are 1609.34 or 1609 meters in a mile so you divide this factor to get the miles per hour.

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.