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How Much Does a Cloud Weigh?

cloud weighed on a kitchen scale.Do clouds have any weight at all? After all, don’t they float like a balloon in the air filled with helium? If you attach a helium balloon the the platform of a kitchen scale it wouldn’t register any weight at all, so why would a cloud? To answer this, let me ask if you think atmospheric air has any weight, this is actually the more important question. Are you familiar with air pressure the tool known as a barometer are? If yes, then you understand that air DOES carry weight. At 0′ (sea level), the weight, or pressure, of air is approximately 14.5  lb.. PSI (1 km per sq. centimeter).

If air has weight, then it must also possess density, which is the weight of a chosen volume, for example cubic inches or cubic meters. If clouds consist of particles, then they must possess weight and density, correct? The answer to why clouds seemingly “float” lies in the density of the sheer volume of cloud material, being less than the density of a similar amount of dry air. As oil floats above H2O because it possesses less density, clouds seemingly “float” on the air due to the moister air in clouds possessing less density than dryer air.

California Water Use Efficiency

The California program known as “turf and toilet” is financed by the Proposition One water bond, which was approved by California voters. It will carry out Governor Brown’s Executive Order of April on drought to further conserve water use in homes and buildings via replacement of more than ten million sq. feet of landscaping and upgrading water-wasting toilets.

D.W.R. will oversee the 2 rebate programs, which offer a one hundred dollar consumer rebate to discard one toilet per house and up to two dollars per square ft. for replacing lawns. More information at

State Agricultural Water Management Plans

There are an approximately 53 water suppliers that rise to the 25,001+ acre limit representing more than 4 million irrigated acres

There are an approximately 39 suppliers of agricultural water to 10,000 to 25,000 irrigated acres representing about 600,000 irrigated acres.

  • H2O providers >25,000 acres minimum and submitted – 40
  • H2O providers >25,000 acres minimum, notified DWR as in progress – 0
  • H2O providers > 25,000 acres minimum, not submitted – 14
  • H2O providers 10+ -25,000 acres minimum and submitted – 22
  • H2O providers 10+ -25,000 acres minimum, notified DWR as in progress – 8
  • H2O providers 10 + -25,000 acres minimum, not submitted – 9

California Rainfall Deficit

Will the upcoming rainy season put a big dent into California’s precipitation deficits?

The answer is only with lots and lots of rain. As of the beginning of Sept, California is has 5-year rainfall deficits (starting in October 2011) of eight inches in the dryer southeast part of the state to almost fifty inches along the northern coast.  In the State of California, four year rain accumulations  (2011-2014) have been about 54-75% of average during that time. To put the shortfall into perspective, every region in the State is missing at least one years worth of rainfall. In fact, the southern coast of the State is missing about two year’s worth of rain (1.8 years to be precise). This shortfall isn’t so much of a hole as it is a giant canyon.

One yardstick used by the U.S. Drought Monitor group to declare drought is whether rainfall totals are in the lower 20 percent of the available record. For 5-year rainfall totals (October 2011 – September 2016) to get out of the lower 20% of records dating to 1928, precipitation totals from October 2015 to September 2016 must be higher than 135-160% of normal in the Northern part of the State , 160%+ of normal in the southeast to 198% of average in the San Joaquin Valley. This is a alot of rain/snow.

Hoover Dam Frequently Asked Questions (FAQ)

Answers to Frequently Asked Questions about the Dam

Where is Hoover Dam located?Photo of Hoover Dam at night. Click photo for larger view.

In Black Canyon across the Colorado River between Arizona and Nevada, about thirty miles east of Las Vegas, Nevada, and a couple of miles from Boulder City, Nevada.

How high is Hoover Dam?

It is slightly over 725 feet from foundation bedrock to the road on the top. The towers and decor on the parapet soar forty feet above the crest.

How much does the Dam weigh?

More than 6,600,000 tons. (A ton is 2,000 pounds)

What type of dam is Hoover Dam?

Made from concrete, an arch-gravity type, in which the water load is borne by both gravity and horizontal arch action.

What is the water pressure at the base of the dam?

Approximately 45,000 pounds per square foot.

How much concrete did the dam require?

3.25 million cubic yards of concrete! There are more than 4,300,000 yards of concrete within the dam, the power building and related works. This much concrete could construct a monument 100 feet square and 2-1/2 miles tall; would be higher than the Empire State Building; or would provide a standard two lane highway sixteen feet wide, from San Francisco all the way to New York on the East Coast.

Initial concrete used in construction of the dam was set on June 6, 1933, and the final portion on May 29, 1935. About 160,000 cubic yards were added to the dam per month. At the peak, placements were more than 10,000 cubic yards a day, including concrete placed in the intake towers and power plant), and just over 275,000 cubic yards in a single month.

How much cement was required?

In total, more than 5,000,000 barrels. The daily useage during construction of the dam was from 7,500 to over 10,000 barrels. Reclamation had used about 6,000,000 barrels in its twenty-seven years of construction activity before June 30, 1932

Nevada Water Data Set

A rasterized image of depth to groundwater dataset for Nevada. The origin of this dataset is a statewide watertable contour dataset made from watertable contours gathered from the 1940's to 2004 and published in thirty-eight reports from the sixties to 2004, depth to groundwater contours from Static Groundwater Levels of Nevada first published in the 1970's, and depth to groundwater contours of Diamond Valley made available in 2006.

Watersheds and Rivers

Watersheds & Rivers

It is very simple to explain why rivers exists on Earth— gravity! You’ve familiar with “water seeks its own level,” but in reality, water is seeking the centerpoint of the planet, just like everything else is. In more practical terms, water usually seeks to flow directly to the oceans, which are, of course, at sea level. So, wherever on Earth water is, it attempts to flow downhill. With the planet being a very not-level place, water ends up filling the valleys and depressions in the terrain as rivers, streams, and lakes.

When observing the location of rivers and streams and the amount of water flowing in rivers, the key idea is the river’s “watershed”. If you are standing on level ground right now, just look downward. You are standing, and others are standing, within a watershed. To define a watershed, it is the region of land where all water falls into it and it drains away as it goes to the same place. Watersheds are be as small as a footprint or massive enough to engulf all the lands that drain water into the rivers,  that drain into the Bays of the Ocean. Bigger watersheds almost always contain multiple smaller watersheds. It is all dependent on the point of outflow; all of the terrain that drains to the outflow location is the watershed of that outflow location. Watersheds are vital because the river-flow and the quality of water of a river are impacted by things, human-induced or not, occurring in the land area “upstream” of the river-outflow point

Underground Groundwater Flows

There are rivers flowing below our feet … a myth?

Is it an old wives tale that there are rivers of flowing underground, beneath us? Do you think its not true? Actually, it can be categorized as a myth. While there are some caverns, and lava / ice tubes, and even horizontal springs with carrying water, , the bulk of water underground takes up the spaces between rocks and other subsurface material. Generally, water that is underground is similar to water in a sponge. It takes up the the spaces between soil, rock, and other substrate particles. At a depth well below the surface of the land, the space between soil and rock particles can be completely filled with water, creating an aquifer from which water can be pumped from groundwater and used by people.

Water Storage in the Atmosphere

Cycle of Water: Atmospheric Water Storage

A lenticular cloud over New Zealand.
Lenticular cloud / New Zealand.
Photo Credit: Chris Picking

The cycle of water is about storing and moving water on, in, and high above the Earth. While the atmosphere may not be a perfect warehouse of water, it is the pipeline used to transport water around the world. Evaporation / transpiration morph liquid to water vapor, which rises up to the atmosphere on rising currents of air. The cooler temperatures high above allow the condenses the vapor into the clouds and trade winds push the clouds around the globe until the water drops as rainfall to further the water cycle. More than 90 percent of h2O in the atmosphere is created by evaporation from bodies of water, while the other 10 +/- % is the result of plant transpiration.

There is perpetually water in our atmosphere. Clouds are the most visible signals of atmospheric water, but clear air contains water vapor, particles of water too small to be seen by the naked eye. One guess of the volume of h2O in the atmosphere at any time is about approximately 3,000 cubic miles, or 12,800 cubic km. (km3). That may sound substantial, but it represents only about 0.001 percent of the planet’s water volume. If all of the h2O in the atmosphere fell at once, it would cover the globe with only about 1 inch of water.


Colorado River System Reservoir Status

Current Status: Lake Powell

The unregulated inflow volume to Lake Powell in May was 2,377 thousand acre-feet (kaf) (101 percent of average).  The release volume from Glen Canyon Dam in May was 652 kaf.  The end of May elevation and storage of Lake Powell were 3619 ft (81 feet from full pool) and 13.67 maf (56% of full capacity), respectively.  The reservoir reached a seasonal low elevation on March 15th near elevation 3593.85 feet. Since that time the reservoir elevation has been increasing and will continue to increase throughout mid-summer as runoff from snowmelt and precipitation enter the reservoir.

To view the most current reservoir elevation, content, inflow and release, click on: Lake Powell Data.
To view the most current reservoir elevation projections, click on: Lake Powell Elevation Projections.
To view the 2017 progession of snowpack above Lake Powell, click on Lake Powell Snow Chart.
To view the current inflow forecast relative to past inflows, click on Lake Powell Inflow Forecast

Current Operations

The operating tier for water year 2017 was established in August 2016 as the Upper Elevation Balancing Tier.  The April 2017 24-Month Study established that Lake Powell operations will be governed by balancing for the remainder of water year 2017.  Under balancing, the contents of Lake Powell and Lake Mead will be balanced by the end of the water year, but not more than 9.0 maf and not less than 8.23 maf shall be released from Lake Powell.  Based on the most probable inflow forecast, this May 24-Month Study projects a balancing release of 9.0 maf in water year 2017.  Reclamation will schedule operations at Glen Canyon Dam to achieve as practicably as possible the appropriate total annual release volume by September 30, 2017.

In June, the release volume will be approximately 750 kaf, with fluctuations anticipated between about 9,000 cfs in the nighttime to about 15,000 cfs in the daytime and consistent with the Glen Canyon Operating Criteria (Federal Register, Volume 62, No. 41, March 3, 1997).  The anticipated release volume for July is 850 kaf with daily fluctuations between approximately 9,500 cfs and 17,500 cfs.  The expected release for August is 900 kaf with daily fluctuations between approximately 10,000 cfs and 18,000 cfs.

In addition to daily scheduled fluctuations for power generation, the instantaneous releases from Glen Canyon Dam may also fluctuate to provide 40 megawatts (mw) of system regulation.  These instantaneous release adjustments stabilize the electrical generation and transmission system and translate to a range of about 1,200 cfs above or below the hourly scheduled release rate.  Under system normal conditions, fluctuations for regulation are typically short lived and generally balance out over the hour with minimal or no noticeable impacts on downstream river flow conditions.