slacken

Work slackens on a hot day.

Slacken your legs and slowly lie back.

The car has slackened its speed.

slacken discipline; afraid that morale might slacken.

the joints can be tightened and slackened off again.

The runners slackened their pace. Air speed slackened.

We’ve been really busy, but things are starting to slacken off now.

Better have no war for a thousand days than slacken your vigilance for one day.

I slackened the line to let the fish swim. The tension in the board room finally slackened.

But soon, the reins slackened in his hands.

The tempo never slackens in this erudite book.

As economic growth slows, demand for oil would slacken.

But, when the brief summer comes, temperatures rise and winds slacken.

If you move the stick fast enough, you don't have to slacken your pace.

Fudges plump face seemed to slacken, as though somebody had let the air out of it.

He thought awhile, and then asked his crew if it was not time to slacken speed.

What if the financial lifeline allowed countries to slacken the pace of reforms, or made life easier for Iran?

The upward rush of the machine slackened off; a moment later they were hanging motionless in the air.

So that means that temperature difference is slackening or weakening.