Why does moisture accumulate in cold areas?
In cold areas, the air in that location has a raised relative humidity compared to surrounding comparative environments. This correspondingly encourages materials in this higher humidity environment to absorb and retain more water from the air than their warmer counterparts in other areas. If this difference in temperature and humidity is dramatic, this creates visible condensation forming on the colder material. This is in instances where the temperature of the cold materials are at or below the air’s ‘dew point’. However where the temperature and humidity difference is not as extreme, and does not create a dew point, you will not actually see the build up of moisture in those colder areas, but nonetheless there will be a collection of moisture in those areas.