Drought conditions now exist over half of the U.S., with nearly 15 percent of the country in extreme to exceptional drought, officials with the U.S. Drought Monitor say.

The Northwest overall saw some improvement thanks to rain in late winter and spring. The Willamette Valley in Oregon also improved, moving from moderate drought, signified as D1, to abnormally dry, or D0.

Drought intensity is measured on a scale of 0 to 4, with 0 meaning abnormally dry and 4 signifying exceptional drought.

But the southern half of Oregon saw little improvement, remaining in severe to extreme drought.

In a May 6 summary, Mark Svoboda of the National Drought Mitigation Center wrote of the Plains states:

Kansas continues to set the edge of the intense drought that seems to be waking up and pushing rapidly north along with warmer temperatures...Soil moisture and groundwater levels are hurting well in front of the peak demand season, as the cumulative impacts of such an intense multi-year drought are already glaringly evident...The story is even bleaker in the southern Plains, where the heat and drought are even more pronounced and entrenched across western Oklahoma and much of Texas as well...Streamflow and groundwater levels are hurting, given the long duration and sustained intensity of this drought, which is now going on close to four years.

Red forests, blue clouds, green lakes

Satellite images of Earth can be stunning — colorful and often revealing the true beauty of the planet.

But while they may look like photographs snapped by cameras similar to the ones we carry around, they aren't, NASA Earth Observatory scientists say.

From NASA:

A photograph is made when light is focused and captured on a light-sensitive surface (such as film or a CCD). A satellite image is created by combining measurements of the intensity of certain wavelengths of light, both visible and invisible to human eyes.

When we see a photo where the colors are brightened or altered, we think of it as artful (at best) or manipulated (at worst). We also have that bias when we look at satellite images that don't represent the Earth's surface as we see it. "That forest is red," we think, "so the image can't possibly be real."

In reality, a red forest is just as real as a dark green one. Satellites collect information beyond what human eyes can see, so images made from other wavelengths of light look unnatural to us. We call these images "false-color," and to understand what they mean, it's necessary to understand exactly what a satellite image is.

Some satellites are designed to capture natural colors

The so-called Landsat Data Continuity Mission satellite launched a year ago to an altitude of 438 miles began scanning swaths of the planet within a week of its April 2013 launch.

From NASA:



Satellites don't take videos; they capture still images. But in a new mosaic, 56 stills have been stitched together to present a seamless video flyover of what LDCM saw one day in April 2013.

Satellites and drought mitigation

Monitoring a drought can be done on the ground by testing soil moistures and snowpacks or measuring streamflows and reservoir levels.

But NASA is also using satellites to help California keep track of one of the most intense droughts in modern history.

From International Television News:

Scientists said they would deploy imaging tools to measure snowpack and groundwater levels. While much of the United States has experienced torrential rains and heavy snowfall this winter, California is in the midst of a drought, threatening to inflict the biggest water crisis in its modern history. Officials will use images shot from two NASA satellites - one designed to measure precipitation and another that tracks soil moisture levels - that are scheduled to launch into orbit this year.

--Stuart Tomlinson