Featured Research

from universities, journals, and other organizations

Mountain Winds May Create Atmospheric Hotspots

Date:
October 18, 2005
Source:
American Geophysical Union
Summary:
Rapidly fluctuating wind gusts blowing over mountains and hills can create "hotspots" high in the atmosphere and significantly affect regional air temperatures. Such winds can create high-frequency acoustic waves and could stimulate a 1000-Kelvin spike in a short period of time.

Rapidly fluctuating wind gusts blowing over mountains and hills can create "hotspots" high in the atmosphere and significantly affect regional air temperatures. A research paper to be published this month in the Journal of Geophysical Research-Space Physics reports that the actions of such winds can create high-frequency acoustic waves and could stimulate a 1000-Kelvin spike in a short period of time in the thermosphere, at an altitude of 200-300 kilometers. Such exceptional temperature increases would require continuous waves, and the heating rate would likely be diminished with intermittent winds.

Richard Walterscheid and Michael Hickey used a theoretical model of the interaction between rough terrain and wind eddies to suggest that high winds may represent a previously unknown source of acoustic waves in the environment. Ocean waves and earthquakes are known to produce similar waves, which strengthen as they propagate higher in the atmosphere. The authors speculate that the waves can heat the atmosphere at prodigious rates and could account for a large part of the unusual and unexplained high-altitude background heating seen above the mountainous landscape in parts of South America.

"We show that that the acoustic waves generated by gusty flow over rough terrain might be a significant source of heating in the upper atmosphere," Hickey says. "These mysterious so-called 'hotspots' observed above the Andes Mountains could be explained by such acoustic wave heating."

Previous observations near the Andes Mountains in Peru had found that the atmosphere directly above some peaks was approximately 100 Kelvin hotter than in nearby regions and that the difference occasionally reached as much as 400 Kelvin. Other research had recorded similar effects near the Rocky Mountains in Colorado. After comparing simulations of atmospheric gravity waves and acoustic waves, the researchers found that the acoustic waves reached higher altitudes than the gravity waves, leading them to speculate that the acoustic waves constituted a far more plausible source of the observed hot spots. They then identified wind fluctuations as the most likely source of the heating, noting that the upwind waves could only be generated by unsteady wind flow.

They cite further evidence indicating that the high- frequency acoustic waves in the thermosphere originated from the ground, including proof that nighttime atmospheric motion (convection) is not a plausible source of the persistent heating. In addition, they note that only high-frequency acoustic waves could cause the thermospheric heating, as the slower-speed gravity waves are not fast enough to reach the higher altitudes and therefore could not produce the substantial effects at that height in the atmosphere.

The paper indicates that moderately strong winds, reaching speeds of approximately 10 meters per second, can generate wave amplitudes of nearly four meters per second above rough terrain. In addition, the authors found that steeply sloping terrain further enhanced the waves, which are generated by rapid variations in the up-and-down turbulence in the air. Wider hills and those spaced further apart can also have a similar wave- generating effect, but the authors found that the wind effects typically do not propagate vertically near isolated hills as they do around rougher terrain.

The researchers note that there are very few detailed field studies of the wind field over hills at present. They report, however, that models and previous research indicates that even weak interactions from acoustic waves can produce significant effects in the thermosphere.

The research was funded by the Aerospace Corporation and through NASA and NSF grants.


Story Source:

The above story is based on materials provided by American Geophysical Union. Note: Materials may be edited for content and length.


Cite This Page:

American Geophysical Union. "Mountain Winds May Create Atmospheric Hotspots." ScienceDaily. ScienceDaily, 18 October 2005. <www.sciencedaily.com/releases/2005/10/051018075220.htm>.
American Geophysical Union. (2005, October 18). Mountain Winds May Create Atmospheric Hotspots. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2005/10/051018075220.htm
American Geophysical Union. "Mountain Winds May Create Atmospheric Hotspots." ScienceDaily. www.sciencedaily.com/releases/2005/10/051018075220.htm (accessed April 20, 2014).

Share This



More Earth & Climate News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Ark. Man Finds 6-Carat Diamond At State Park

Ark. Man Finds 6-Carat Diamond At State Park

Newsy (Apr. 18, 2014) An Arkansas man has found a nearly 6.2-carat diamond, which he dubbed "The Limitless Diamond," at the Crater of Diamonds State Park. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins