squeal on cold and humid startup

I live in Southern California near the beach with marine layer effect in the mornings. Recently on cool mornings with air temp between 40-55 degrees there is a squeal sound coming from the upper pulley / belt. ( See Photo ). The squeal goes away within 1 min. and usually doesn't happen on the second start of the day. I sprayed WD 40 on the pulley & belt and it started with no squeal for a day. HAH LOL.

The belt seems solid with no signs of cracking or aging.

1st Question: What pulley is this?

2nd Question: What belt does it control?

3rd Question: What would you do about it if it was your truck?

 

Power steering pump. Ensure the belt is tight. They normally squeal if they are a bit loose.