Looks puzzling - I know little about these things - but have you checked your windscreen washer bottle / feeder tubes are not leaking and throwing spray within the engine compartment when activating the washers - or it may be a small leak from a water hose? Also - is the car parked outside overnight? Trial and error above and below the hood I guess.
Dry the engine and park under cover overnight if possible - garage.
Dry the engine and park under cover overnight if possible - garage.