The Daily Croissant

"This image from the Landsat 5 satellite was acquired on October 27, 2011. The false-color view shows the high desert—bare soil and sparse vegetation appear in shades of brown and pink—and the deep green vegetation on the west side of the Cascade Mountains. The one blue spot is the glacial cap of Mount Hood.

The transition from green to brown is indicative of a rain shadow. Winds blow in from the west, carrying moisture from the Pacific Ocean. As the air moves across the landscape and up into the high elevations of the Cascade Range, air pressure decreases. The air cools and becomes unable to hold as much moisture, causing water to fall out as rain or snow. For this reason, the Cascades spend most of the year blanketed by cloud cover, and the frequent precipitation provides ample water for lush vegetation and gigantic trees. 
On the eastern, leeward side of the mountains, the elevation drops, the air warms, and the air pressure increases. This effectively shuts off the rain because the air can better hold the remaining moisture. This effect is called a rain shadow and is largely responsible for the desert landscape beyond the mountains."

by Steven L. Templeton 

"The photo above shows a cloudburst I observed just before sunset in Jones County, Texas on September 17, 2011. This rain shaft looked more foreboding than was actually the case and indeed any rain in drought-stricken Texas was welcome. January through July of 2011 was the driest six-month period ever recorded in Texas. Additionally, the summer of 2011 was the hottest on record. Convective storms can sometimes produce very localized rains; a deluge in a particular spot but only a few drops just a few hundred yards away."

Photographer : Hector Fabian Garrido

"The photo above showing a sensational display of lenticular clouds was snapped near La Rioja, Argentina, at the base of the Andes Mountains, on September 9, 2011. I was doing seismic testing just after sunrise and was taken aback by the gold and tawny wave clouds that appeared across much of the sky. These lenticulars took shape to the lee (east) of the Andes, just west of my location -- the Sun was behind the camera. Lenticular clouds are generally orographic in origin, forming in lee waves when air is forced to rise over elevated terrain. On this early spring morning, the smooth structure of the waves, the illumination by the low Sun, and the absence of other types of clouds, gave the sky a surreal look."