When does an object have negative velocity

When it is moving to the left. the sign of the velocity specifies the direction of the object/ particle

When it's moving in the direction opposite to the direction you defined as positive when you started working the problem.

The horse latitudes-high-pressure zones about 30 degrees north and 30 degrees south of the equator.-warm air traveling away from the equator cools and sinks-weather tends to be clear and drythe doldrums-low-pressure near equator-air rises and spreads out toward the poles-rising moist air produces clouds and heavy rainthe westerlies-blow from the west-move from the horse latitudes toward the poles.-bring storms across much of the united statesthe tradewinds-blow from the east-move from the horse latitudes toward the equator  -strong, steady winds

Apossible long term health effects of stress would be work