Dr. Jeff Masters' WunderBlog

Haboob!

Posted by: Dr. Jeff Masters, 2:46 PM GMT on May 03, 2005

The name haboob comes from the Arabic word "habb", meaning wind, and refers to a sudden dust storm triggered by the cold-air outflow from a decaying thunderstorm. Cold air from the mid-troposphere is dragged down by falling rain inside the thunderstorm. When the cold air hits the ground, it spreads out in all directions. If there is a dusty desert area below, the strong gusty winds of this cold air outflow will pick up the dust and mix it up to great heights. The edge of this cold air (called a "gust front") will then appear as a wall of dust up to 3000 feet high, moving across the desert at speeds of up to 50 mph. Haboobs are commonly seen in the Sahara desert, Iraq, Australia, and the Southwestern United States.

Dust Storm and Barn (PastorJohn)

Dust Storm and Barn in Cheyenne County Kansas

Dust Storm (Aaronjef)

Dust storm passing through Griffith NSW Australia

DUST STORM PICTURE #2 (YELLOWSUN)

THIS DUST STORM WAS MOVING IN FAST. HERE IS ANOTHER PICTURE OF IT AS IT APPROACHES WAKEENEY.

Categories: Atmospheric Phenomena

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1. TomP 12:03 PM GMT on May 04, 2005
Let me ask a dumb question. "Cold air dragged down from the troposphere" sounds like the story in "The Day After Tomorrow". Air dragged down from the troposphere is still subjected to adiabatic heating due to compression, isn't it? Just how cold is the air in these outflows that lead to a haboob? Member Since: February 16, 2004 Posts: 0 Comments: 0

2. TomP 12:09 PM GMT on May 04, 2005
These are incredibly cool pictures, by the way. Member Since: February 16, 2004 Posts: 0 Comments: 0

3. Dr. Jeff Masters, Director of Meteorology (Admin) 9:06 AM EDT on May 04, 2005
True, air dragged down from the troposphere is still subjected to adiabatic heating due to compression, and warms on descent. But in most cases, the air sucked down starts off colder than its enviroment, since it comes from the cold side of the cold front that is triggering the thunderstorm. Plus, the air cools even more as some of the rain in it evaporates, sucking out latent heat energy. When the air reaches the ground, it's common for it to be 10 or even 20 degrees F colder than the surrounding warm, moist air. The quote in "Day After Tomorrow" where they talk about this issue is my favorite example of bad science in Hollywood. In the movie, the superstorm sucks vast quantities of frigid upper atmospheric air down to the surface, flash freezing any living thing caught outside. However, any graduate of a high school physics course could tell you that the air would warm on its descent in response to the requirements of the Ideal Gas Law, and would never be able to flash freeze anything. One scientist in the movie does remember his high school physics and asks, "But wouldn't the air warm as it descends?" But the senior scientist replies, "No, it's moving too fast!" Sorry, guy, but the Ideal Gas Law applies no matter how fast the air is moving. If you were on my thesis committee, I'd kick you off. Dr. Jeff Masters

4. TomP 2:48 AM GMT on May 05, 2005
Thanks; I assumed the explanation would be along those lines. So, is it possible to predict a haboob? If not, is it at least possible to recognize conditions conducive to a haboob? If so, is it just a matter of recognizing that there's a pool of very (relatively) cold air aloft that would produce the habob if "dragged down"? FWIW, I'm theoretical chemist trying to understand practical meteorology; I'm comfortable with a lot of the underlying physics, but haven't seen it applied to the weather, for the most part. Member Since: February 16, 2004 Posts: 0 Comments: 0

5. Dr. Jeff Masters, Director of Meteorology (Admin) 8:30 AM EDT on May 05, 2005
I believe that the most favorable conditions for a haboob are the presence of very dry air around a thunderstorm, to increase the amount of evaporational cooling that can occur. Since cold fronts usually don't make it far enough south to make it to desert areas, the presence of a cold pool of air aloft is usually less important to the formation of a haboob. Jeff Masters

6. Y2KOTA 6:00 AM GMT on May 09, 2005
Those 3 shots are great due to they show buildings in the fore ground to give a idea of size of the storms.

7. jak74 3:14 PM GMT on May 11, 2005
Interesting stuff! Not for nothing, but I was always understood that the word "haboob" came from the Arabic word "hebbe" which means "blown," not "phenomena" as you wrote. Certainly not important, but I was curious if my old meteorology textbook from college steered me wrong all these years. Any thoughts?

8. Dr. Jeff Masters, Director of Meteorology (Admin) 4:26 PM GMT on May 11, 2005
You're right, Jak74, my "Glossary of Weather and Climate" says haboob comes from the Arabic word, habb, meaning wind (or blow). You can't believe everything that turns up on a Google search! Jeff Masters

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