Head in a Cloud

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A Summary of “Effect of Dynamics on Mixed-Phase Cloud: Theoretical Considerations”- Korolev & Field

February 11th, 2008 by BDA · 2 Comments

Editor’s Note: The following is the first in a series of posts by undergraduate students in the course “Physical Meteorology: Atmospheric Radiation and Cloud Physics” that I am teaching at Metro State College of Denver. I hope you enjoy! -Sean Davis
The following is a brief overview of the paper “The Effects of Dynamics on Mixed-Phase Clouds: Theoretical Considerations” written by Alexei Korolev and Paul R. Field which appears in the January 2008 issue (Volume 65 pg. 66-86) of Journal of the Atmospheric Sciences. This paper furthers existing research of mixed-phase clouds, specifically the activation of liquid water within non-equilibrium state ice clouds. The liquid-activation process within ice clouds is complex process is dependent on many variables. An accurate parameterization will increase model validity especially affecting precipitation prediction and aviation safety.

In a mixed-phase environment basic thermodynamics tells us that because the saturation vapor pressure over ice is less than that over water, liquid water will deposit itself onto ice crystals until there is no more liquid water. However, direct measurements have detected stable liquid layers within ice clouds and this paper studies the necessary requirements for stable liquid layers to exist under three specific conditions which are uniform vertical ascent, harmonic vertical oscillation, and turbulent motion.

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→ 2 CommentsTags: modeling · MTR3440

The Tragedy of the Commons: Peak Oil and Climate Change

February 6th, 2008 by jason english · 10 Comments

“The Tragedy of the Commons” was published in Science in 1968 by Garrett Hardin. Hardin argued that some problems have “no technical solution”. A technical solution is something that can be solved by technology or the natural sciences, demanding no change in human values or ideas of morality. The problem Garrett was referring to was exponential human population growth. With population growth comes increases in human needs for agriculture, energy, shelter, etc. As the earth is a finite size, this would result in a drawdown of the earth’s resources, and eventual human suffering on a global scale. Since decision of family size are made within the narrow framework of one’s personal life, the slight additional load on the earth is temporarily overlooked, until it the earth reaches a critical point, and all of humanity suffers. Garrett argued that the only solution to this eventual problem is “mutual coercive agreement”, e.g. we need to all agree to limit family size for the sake of future generations.

Fast forward 40 years. Clearly we have no limitation of family size (except in China). Fortunately, human population growth has slowed somewhat due to family planning, education, affluence, gender equality, and shifting cultural norms. However, the population is still at 6.5 billion humans and projected to reach a peak of 9 billion in 2050. There are various projections of the sustainable carrying capacity of the earth which range from 1 to 6 billion humans – all projections which do not encompass future human population. The impact on the earth by humans is Population x Consumption, and economic growth, energy usage, land usage, raw materials, etc have increased.

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→ 10 CommentsTags: ATOC Journal Club · climate · general interest · global warming

Phinully Done (Ph.D.)! Ready for the New Year!

January 21st, 2008 by Sean Davis · 1 Comment

After a bit of a hiatus, Head in a Cloud is back in action for the new year. A large reason for the hiatus is that I recently (well… last November to be exact) finished my Ph.D., which as one might imagine causes a bit of strain on one’s life. …In fact, I feel like I’m just now really recovered from it. I’m glad to be back in the blogosphere, and look forward to an active year here at HIAC!

So what’s in store for the new year? Well, hopefully the ATOC Journal Club will be up and running shortly and we can resume bringing you summaries of the presentations/discussions that go on there. In addition to the journal club posts, there will be semi-regular guest posts this spring. As it turns out, I am teaching a course on Cloud Physics and Radiation at the Metropolitan State College of Denver, and am going to perform an experiment to see if I can make blogging work as an educational tool for this class. The class site is here if you are interested in the topics, by the way. There’s not much there right now, but I will eventually put lectures up (although I must say, they won’t be complete lectures– I can’t stand the “everything in powerpoint” method). Anyways, the plan is to have students post blog entries here on current topics related to clouds, weather modification, and atmospheric radiation/optics/electricity. It should be fun!

In the meantime, if you haven’t heard of it, or visited it in a while, check out PhD Comics. It’s sort of like Dilbert for grad school and academia.  I remembered being introduced to it a while back, but I haven’t kept with it for a while.

→ 1 CommentTags: ATOC Journal Club · general interest · humor

Climate engineering

December 6th, 2007 by Jamison A. Smith, Ph. D. · 8 Comments

For journal club this week, I discussed an editorial about climate engineering [Crutzen, 2006] and a response to  this editorial [Bengsston, 2006].

Crutzen proposes injecting SO2 into the stratosphere to counteract global warming caused by the combustion of fossil fuels.  The SO2 should oxidize to form sulfuric acid, and this acid will condense to form aerosol that scatter incoming solar radiation, thus providing a cooling effect.

The proposal appeared to be feasible and effective.  My strongest criticism of the proposal was that the climate-control aerosol will destroy stratospheric ozone.

Bengtsson [2006] provided a few extra criticisms. Two of the strongest criticisms were:

1) We’d have to keep injecting this SO2 every year for centuries until the atmospheric CO2 concentration recovered back to preindustrial values.

2) The acidification of the ocean from the dissolution of excess CO2 would result in undersaturation of minerals in the ocean. I think this undersaturation would result in the dissolution of carbonate animal remains which would shut down the burial of C in the ocean sediments, thus providing a positive climate feedback to CO2, but Bengtsson didn’t actually explicitly state this positive feedback.

I think oceanic acidification would result in other problems as well, like maiming or killing oceanic biota.

- Jamison A. Smith, Ph. D., December 6, 2007

→ 8 CommentsTags: aerosols · ATOC Journal Club

Know anything about carma.org (not the model)?

November 16th, 2007 by Hasenkopf · No Comments

Granted I don’t study present-day Earth’s climate change, but I was still surprised that the first I heard of a new website carma.org was through CNN yesterday rather than through the scientific community. Carma.org is a repository of CO2 emission and other energy consumption data by geographical locations all across the world. Have any of you heard of this through other sources than CNN?? Any idea how reliable the data is? I haven’t looked through this extensively yet, but The Digging Deeper section is a cool interface and I do like that, IF the data is accurate, it is made available like this to the world. Anyways, I’d really like to hear peoples’ thoughts on what they think of the site; I noticed none of the blogs (linked on the left of this page) have mentioned it yet. Read on for the “rambling” portion of the article that is tangential to the topic above. :o) [Read more →]

→ No CommentsTags: general interest · Uncategorized