Aerosols

El agujero de ozono

Sergio Cáceres Mercado - 

Corría la década de los ochenta. Había esperanza de que la Guerra Fría terminara y con ella la amenaza de una catástrofe termonuclear. Sin embargo, una noticia ensombrecía esa esperanza: en el Polo Sur un agujero en la capa de ozono encendía una nueva alarma medioambiental. Según los investigadores, la destrucción de dicho gas de debía a sustancias producidas por el ser humano, en especial los usados en aerosoles y otros artefactos.

Como nunca, el debate sobre los efectos dañinos de la acción humana estuvo al orden del día. Es que la falta de ozono significaba una mayor entrada de rayos ultravioletas provenientes del Sol, lo que a su vez aumentaba la posibilidad de cáncer en la piel. Demás está decir que el miedo se instaló en todos.

Desde ese momento una serie de medidas preventivas fueron tomadas, varias de ellas a partir de reuniones de expertos patrocinados por la ONU y sus Estados miembros. Aquellas sustancias que afectaban a la capa de ozono fueron reducidas a su máxima expresión y se buscaron reemplazantes que no tuviesen sus efectos perjudiciales.

Ahora, más de tres décadas después, nuevas investigaciones revelan que la capa se está recuperando. ¿Significa esto que las políticas de prevención a nivel mundial dieron el resultado esperado? Todo apunta a que sí.

Es de necios negar que ciertas acciones humanas afecten negativamente el medioambiente. Sin embargo, cuando hablamos de escala mundial surgen los desacuerdos entre expertos, además de que los intereses económicos y políticos juegan su propio partido también. Ejemplos de esto lo vemos en temas como el calentamiento global, los alimentos genéticamente modificados y las ondas electromagnéticas, entre otros.

A partir de estos nuevos datos con la capa de ozono, ¿se apoyarán con más intensidad los otros esfuerzos que combaten la destrucción de los ecosistemas y protegen la diversidad biológica? En realidad, nada es seguro. Aquellos intereses que llevaron a que nuestro planeta se deteriore a niveles alarmantes siguen muy vigentes. Ni siquiera los datos científicos más duros sirven como argumentos. Muchas veces la ciencia misma también se presta a la especulación.

La capa de ozono sigue ahí, solo que un poco más pequeña. ¿Fuimos nosotros los que la que la creamos? ¿Somos nosotros quienes la estamos revirtiendo? Todavía queda mucho por debatir, y también por destruir.

This image shows the emission and transport of dust and other aerosols to the Southern Ocean on Dec. 30, 2006. Dust is represented with orange to red colors, sea salt with blue, organic and black carbon with green to yellow, and sulfates with brown to white.

Credit: William M. Putman and Arlindo M. da Silva (NASA/Goddard Space Flight Center)

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Light rain after a dry spell often produces a distinctive earthy scent called petrichor that is associated with plant oils and bacteria products. How these chemicals get into the air has been unclear, but new research suggests that the mechanism may come from the rain itself. When water falls on a porous surface like soil, tiny air bubbles get trapped beneath the drop. These bubbles rise rapidly due to buoyancy and, upon reaching the surface, burst and release tiny droplets known as aerosols. Depending on the surface properties and the drop’s impact speed, a single drop can produce a cloud of aerosol droplets. The research team is now investigating how readily bacteria or pathogens in the soil can spread through this mechanism. Other human-focused research has already shown that these tiny aerosol droplets can persist in the air for remarkably long periods and may help spread diseases. (Video credit: Massachusetts Institute of Technology; research credit: Y. Joung and C. Buie; submitted by Daniel B and entropy-perturbation)

Moonrise in Haze

The photo above shows a moonrise sequence above an oil tanker in Casco Bay, Maine, as observed on September 18, 2013.

The Moon was one day shy of being a full Harvest Moon. Initially, only a faint outline of the lunar disk can be observed since the Moon is rising through a dense layer of haze. When the Moon (or Sun) is close to the horizon the increase of path length acts to redden the moonlight that reaches our eyes.

However, if enough haze particles or other aerosols are available the moonlight may be completely extinguished. On this evening the Moon was invisible until it was approximately 10 degrees above the horizon. Note that the Moon is moving through the Belt of Venus (or anti-twilight arch) – the pink band of scattered sunlight that sits atop the rising Earth’s shadow. - Sherry Bateman, John Stetson

Portrait of Global Aerosols

Aerosols, clouds of microscopic particles suspended in air, are key players in the health of our atmosphere and climate. They also happen to make really pretty sunsets. Aerosols can scatter sunlight back into space, which can cool the planet, or seed dangerous chemical reactions like those that destroy ozone. Understanding how different types of aerosols move and react in our atmosphere is crucial to smart climate science.

The image above is a NASA supercomputer simulation of different aerosols moving around Earth. It sort of looks like someone painted Earth and then swirled the colors around before they dried, doesn’t it?

Dust is red (remember that half the Amazon gets its nutrients from African aerosols!), smoke from fires is green, volcanic eruptions are white, and sea salt is blue.

See the beautiful hi-res version of the image here. Phil Plait has more explanation at Bad Astronomy (now at Slate!)

If you loved this visualization, revisit NASA’s Van Gogh-esque Perpetual Ocean current simulation. Beautiful stuff. 

(via NASA)

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It was just another ugly, polluted day in Los Angeles, with total chemcover morning till night.  See the faint chemhalo around the morning sun?  I can tell when the clouds are man made.  The sun always shines through in this same way and the sky looks like someone scribbled over it with a graphite pencil.  It looks like heavy metal particles to me, although cleverly disguised as clouds.  The Weather Space also accurately reported aerosol levels in the red for Southern California today.  The stuff was so thick you couldn’t even see the sprayers at work.  It is almost certain we’ll get a good dousing of heavy metals at tomorrow’s chemtrail protest.  Hope to see you all there!

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The motions of Earth’s atmosphere move more than just air and moisture. As seen in this animation built from NASA satellite data, the atmosphere also transports large amounts of small solid particles, or aerosols, such as dust. Each year the wind carries millions of tons of Saharan dust across the Atlantic, depositing much of it in the Amazon basin. This provides much needed nutrients like phosphorus to plants and animals in the Amazon; check out this video from the Brain Scoop to see what happens in areas that don’t receive these nutrients. Dust is only one of many sources for atmospheric aerosols, though. Sea salt, volcanic eruptions, and pollution are others. All of these aerosols serve as potential nucleation sites for raindrops or snowflakes, and their transport all around the globe by atmospheric winds means that seemingly local effects–like a regional drought or increased pollution in developing countries–can have global effects. (Video credit: NASA Goddard; submitted by entropy-perturbation)

When a volcano erupts, the concentration of aerosols in the stratosphere increases. Aerosols play an important role in Earth’s climate, reflecting or absorbing sunlight.

Canada’s instrument OSIRIS has measured the impact of nine volcanic eruptions since the beginning of its mission in 2001.

More info here.
Photo: NASA / Aqua – MODIS

Credit: Canadian Space Agency’s Facebook Account