When an object is cool and warm air touches the cool object, the air cools and droplets of water forms on the outside of the object.Relative humidity is a comparison between how much water is already in the air compared with how much water the air is able to hold at a certain temperature.Another large source of water vapor in the air is when the plants absorb water through their roots and stems into their leaves.Characteristics of water vapor include it being 
colorless, odorless, invisible, and has no taste.All of the water in the air, whether it is from the world's ocean and other bodies of water, the water 
on a mirror following a hot shower, or the water a 
plant releases into the air; it is all called humidity 
because it is the amount of water vapor in the air.When the air is filled with this water, the amount of water in the air can be measured.The air could be become foggy or misty, or dew may appear on the 
grass in the mornings.The molecules of the water is 
absorbed by the Sun's energy near the surface of the water which then evaporates into the air.The process of plants releasing water into the air is called transpiration.Another measurement used is called relative 
humidity.Examples 
include moisture on the outside of a cold glass, or a mirror after a hot shower, which is also called condensation.Humidity is the amount of water vapor in the air.Water vapor gets into the air day through the process of evaporation.In summary, the water in the air is called water 
vapor.Plants also release water into the air during a process 
called transpiration.Finally, all of the water vapor in the air is called humidity.A comparison between how much water is already in the air compared with how much water the air is able to hold at a certain 
temperature is called relative humidity.When this happens there could be rain, snow, fog, or dew.This water in the air is called water vapor.Water vapor is in the form of a gas.When the in the air turns into a gas it is called evaporation.Ocean water, and other bodies of water, is turned into water vapor using the energy from the sun.The changing of a gas into a liquid is called condensation.An example of condensation is the water which covers a mirror following a hot shower.When the air can no longer hold the water vapor several things can happen.It may rain or snow depending on the temperature.Another problem with too 
much water vapor in the air, especially in the 
summer, is it becomes very uncomfortable and 
people began to sweat very easily.Water vapor in the air forms when cold air and warm air come in contact with each other.When this water is turned into a gas and is released into the air it is called evaporation.This is the result of the hot and cold air coming into contact with each other.The leaves then give off water.