At a certain temperature, the amount of water vapor in a cubic meter of air (i.e. the absolute humidity, later slightly) rises to a certain saturation point, at which point it condenses into droplets.
At the above saturation state, we call the relative humidity at that time 100%; If its moisture content is only half of that of saturation, its relative humidity is 50%, thus different relative humidity can be deduced. Note that the temperature is higher (or lower), the moisture content in the air to a little more (or less), to (or can) reach a state of saturation and dews. Therefore, after loading in ports with very high temperature and relative humidity, the vessel will set sail. If the vessel is not ventilated along the way and sails into the water area with very low temperature, the moisture in the cabin air is likely to condense into small drops on the cold hull plate.
On the contrary, if the cargo is loaded at a very low temperature port, the ship will set sail immediately. If the cargo is not ventilated along the way and it arrives at a port with very high humidity and high relative temperature, if the cargo is opened suddenly or strongly ventilated, the moisture in the air outside the cabin will condense into small drops on the cold cargo surface. Since at a certain temperature, the moisture content in the air per unit volume is large enough that the relative humidity is 100%, it will condense into water droplets. On the contrary, when a certain amount of water vapor in a unit volume of air drops to a certain temperature in the original air temperature, it will condense into water droplets, which is called dew point temperature. The dew point temperature can be read out from the instrument or checked in the table with the dry and wet temperature as two arguments.