Humidity Humidity Humidity is the amount of water vapour present in air. Water vapour, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. The amount of water vapour needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapour contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 grams of
Water in California million tons. About one-third of that, around 700,000 tons, went to China, Japan took about the same amount and Saudi Arabia bought 5,000 tons. Alfalfa farmers pay about $70 an acre-foot, in Los Angeles that same amount of water is worth $1000 per acre-foot. In 2012, California exported 575,000 tons of alfalfa to China, for $586 million. Other common crop water use, if using all irrigated water: fruits and nuts with 34% of water use and 45% of revenue, field crops with 14% of water and 4% of revenue, pasture forage with 11% of water use and 1% of revenue,