weather conditons over an extended period of time
the weather man
the % of moisture the air holds relative to what it would hold @ a given temp.
moisture in the air condenses on small particles of dust or other solids in the air
water vapor that condenses and falls to the ground as rain etc.
heavy rainstorms with thunder and lightning
water molecules rub togther during sorms and static electricity is produced.
lightning causes the air to heat and expand