Share

River and Mountain Valley Fog From Space

By Chris Dolce
Published: October 18, 2013

NOAA

Fog in the river and mountain valleys of Pennsylvania and New York on Aug. 20, 2013. Image credit: SSEC/NOAA

Spreading like veins on the earth's surface, fog can be a spectacular sight from space.

Specifically, we're talking about river and mountain valley fog. The slideshow above and the animation below illustrate the unique views that valley fog produces from above.

(MORE: How Does Fog Form?)

Mountain valley fog is just a type of radiation fog.

Radiation fog forms at night when winds are light, skies are clear and there is moist air near the surface of the earth. As the air cools at the surface, it becomes saturated, leading to the formation of fog.

In mountain locations, air from elevated areas near mountain valleys cools and becomes more dense and heavy. As a result, the cold air drains into the valleys below where it continues to cool and the radiation fog forms.

River valleys are also prone to the formation of radiation fog. However, sometimes the fog found over rivers, streams and lakes is caused by steam fog.

Steam fog forms when cool air moves over and mixes with the relatively warm and moist air near the surface of the water. The moist air then cools and becomes saturated, causing fog to form.

At times, fog in river valleys can be from a combination of radiation fog and steam fog.

River Valley Fog Animation

Fog on Satellite

Satellite loop of fog dissipating in the river valleys of southern New York and northern Pennsylvania on Aug. 20, 2013. Credit: NOAA/SSEC


Featured Blogs

Tropical Storm Bertha Hits the Lesser Antilles

By Dr. Jeff Masters
August 1, 2014

The center of Tropical Storm Bertha was passing between the Lesser Antilles islands of Martinique and Dominica near 4 pm EDT on Friday, but has brought little in the way of strong winds or heavy rain to the Lesser Antilles Islands so far. As of 4 pm, Martinique had received 0.35" of rain, with top winds of 22 mph. Dominica had a wind gust of 43 mph at 4 pm EDT.

National 24-hour Precipitation Records

By Christopher C. Burt
August 1, 2014

Earlier this week, on July 28th, both Holland and Germany saw some incredible rainfalls that approached their respective all-time national records for greatest 24-hour precipitation totals. Here are some details on these events as well as a ‘potted’ list of some other national records of such.

Live Blog: Tracking Hurricane Arthur as it Approaches North Carolina Coast

By Shaun Tanner
July 3, 2014

This is a live blog set up to provide the latest coverage on Hurricane Arthur as it threatens the North Carolina Coast. Check back often to see what the latest is with Arthur. The most recent updates are at the top.

Tropical Terminology

By Stu Ostro
June 30, 2014

Here is some basic, fundamental terminology related to tropical cyclones. Rather than a comprehensive and/or technical glossary, this represents the essence of the meaning & importance of some key, frequently used terms.

2013-14 - An Interesting Winter From A to Z

By Tom Niziol
May 15, 2014

It was a very interesting winter across a good part of the nation from the Rockies through the Plains to the Northeast. Let's break down the most significant winter storms on a month by month basis.

What the 5th IPCC Assessment Doesn't Include

By Angela Fritz
September 27, 2013

Melting permafrost has the potential to release an additional 1.5 trillion tons of carbon into the atmosphere, and could increase our global average temperature by 1.5°F in addition to our day-to-day human emissions. However, this effect is not included in the IPCC report issued Friday morning, which means the estimates of how Earth's climate will change are likely on the conservative side.