Other contributors have said "How does the dense fog off of Newfoundland ovccur?" is the same question as "Why Newfoundland has thick fog all the year around?" If you believe that these are not asking the same thing and should be answered differently, click here
Why Newfoundland has thick fog all the year around?
Because two ocean currents meet- the cold Labrador Current and the warm Gulf Stream. The associated airmasses mix- warm air from Gulf Stream is warm and moist, Labrador cold, so the moisture in the warm air cools and condenses.
Sudan has a tropical climate. Seasonal variations are most sharply defined in the desert zones. Annual rainfall, most of which occurs mid-June and September. So I think it is not hot all throughout...