Tag Archives: clouds

Wildfires could ‘seed’ new clouds with the particles they release

‘Ice’ is not the first thing that pops into your mind when thinking of wildfires, is it? And yet, new research is pointing to a link between such fires and the teeny tiny bits of ice that form clouds.

Image credits Sippakorn Yamkasikorn.

A new study is looking at the link between wildfires and ice-containing clouds like cumulonimbus or cirrus, the main drivers of continental precipitation. According to the findings, these clouds require microparticles to start forming — which a wildfire can supply in great quantities.

Ashes to rain

Cloud formation is a complex phenomenon, one that can shift quite significantly depending on conditions such as temperature or atmospheric dynamics. The clouds you’re used to seeing, for example, start their lives around very tiny particles, known as ice-nucleating particles (INPs). These can be anything from bacteria to minerals, just as long as they’re very tiny.

And that’s why the team was interested in studying how wildfires could influence the genesis of such clouds: wildfires can generate tons and tons of small particles. Because of this, they argue that wildfires could have a very important role to play in the dynamics of clouds, at least on a local level.

In order to find out, one study analyzed the plumes of the 2018 wildfires in California (western US) from samples taken at high altitudes, where the particles it contains might directly affect cloud formation. In very broad lines, this study found that INP quantities can become up to 2 orders of magnitude higher in a wildfire smoke plume compared to normal air. However, this didn’t account for the types of particles involved. Fires can produce a wide range of particles depending on the fuel they’re burning, their location, the specific conditions this burn is taking place in, and its temperature. One useful bit of information we can glean from this study is that the INPs were dominated by organic materials.

Spherical tar balls accounted for almost 25% of INPs in certain conditions, although this seems to vary widely with the type of fuel and the type of fire involved — understanding how they factor in is still “an open question,” according to the researchers.

Wildfires are predicted to become much more common in the future due to climate change, the team explains, so understanding how they can influence clouds (and thus, precipitation patterns) will do us a lot of good in the future. So far, the papers showcase that they can lead to very high levels of INPs accumulating in the troposphere, which could in turn influence how clouds and rain behave.

At this time, however, we need more modeling and sampling studies to understand these mechanisms in detail, and how they influence the world around us.

The paper “Observations of Ice Nucleating Particles in the Free Troposphere From Western US Wildfires” has been published in the journal Journal of Geophysical Research: Atmospheres.

Antarctic ozone hole at its smallest recorded size ever

The ozone hole over the Antarctic registered its smallest annual peak on record (tracking began in 1982) according to an announcement by the National Oceanic and Atmospheric Administration (NOAA) and NASA on Monday.

Image credits NASA Ozone Watch.

Each year, an ozone hole forms during the Southern Hemisphere’s late winter as the solar rays power chemical reactions between the ozone molecules and man-made compounds of chlorine and bromine. Governments around the world are working together to cut down on the ozone-depleting chemicals that created this hole, and it definitely helps.

However, the two agencies warn that we’re still far from solving the problem for good. The small peak in the ozone hole’s surface likely comes from unusually mild temperatures in that layer of the atmosphere seen during this year, they add.

Good but not done

NASA and NOAA explain that the ozone hole consists of an area of heavily-depleted ozone in the upper reaches of the stratosphere. This hole is centered on Antarctica, between 7 and 25 miles (11 and 40 kilometers) above the surface. At its largest recorded size in 2019, the hole extended for 6.3 million square miles (September 8) and then shrank to less than 3.9 million square miles (during the rest of September and October). While that definitely sounds like and is a lot of surface, it’s better than it used to be.

“During years with normal weather conditions, the ozone hole typically grows to a maximum of about 8 million square miles,” the agencies said in a news release.

It’s the third time we’ve seen a similar phenomenon — weather systems slowing down stratospheric ozone loss — take place over in the last 40 years. Below-average spikes in the size of the ozone hole were also recorded in 1988 and 2002.

The stratosphere’s ozone layer helps deflect ultraviolet (UV) radiation incoming from the sun. That’s very good news if you like being alive as UV rays are highly energetic and will cause harm to the DNA of living organisms. UV exposure can lead to skin cancer or cataracts for animals and damages plantlife.

A host of chemicals that used to be employed for refrigeration, including chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs), break down ozone molecules in the stratosphere — which exposes the surface to greater quantities of UV. These compounds can last for several decades in the atmosphere and are extremely damaging to ozone during that time, breaking it down in huge quantities.

Humanity bunched together to control the production and release of such chemicals under the Montreal Protocol of 1988, which has drastically reduced CFC emissions worldwide. The ozone layer has been steadily recovering since then, but there’s still a long way to go.

“It’s a rare event that we’re still trying to understand,” Susan Strahan, an atmospheric scientist at the NASA’s Goddard Space Flight Center in Maryland, said in a news release. “If the warming hadn’t happened, we’d likely be looking at a much more typical ozone hole.”

The reactions that break down ozone take place most effectively on the surface of high-flying clouds, but milder-than-average temperatures above Antarctica this year inhibited cloud formation and made them dissipate faster, NASA explains. Since there were fewer clouds to sustain these reactions, a considerable amount of ozone made it unscathed. In a divergence from the norm, NOAA reports that there were no areas above the frozen continent this year that completely lacked ozone.

Warming in the shape of “sudden stratospheric warming” events, were unusually strong this year, NOAA adds. Temperatures in September were 29˚F (16˚C) warmer than usual (at 12 mi/19 km altitude) on average, “which was the warmest in the 40-year historical record for September by a wide margin” according to NASA.

Warmer air weakened the Antarctic polar vortex, a current of high-speed air circling the South Pole that typically keeps the coldest air near or over the pole itself, which slowed significantly (from an average wind speed of 161 mph / 260 kmph to 67 mph / 107 kmph). The slowed-down vortex allowed air to sink lower in the stratosphere, where it warmed and inhibited cloud formation. It’s also likely that it allowed for ozone-rich air from other parts of the Southern Hemisphere to move in.

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Watch the Grand Canyon overflowing with clouds in the wake of atmospheric inversion

Filmmaker Harun Mehmedinovic recorded this breathtaking video of the Grand Canyon turned sea-of-clouds in the wake of a total temperature inversion and a particularly chilly night.

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For the most part, air is warm near the ground and gets progressively colder the further up you go, because it’s the ground that radiates heat. Per thermal dilation works, however, the low layer of air tries to push its way up once it gets warm enough. This upward motion ultimately culminates in the formation of clouds, as the upward drafts of air carry moisture from the ground up to colder layers where it condenses. This effect leads to a variety of different types of clouds. 

But in some very rare conditions, the bodies of air can undergo a spectacular phenomenon known as a total temperature inversion. In case the name wasn’t a dead giveaway, it basically consists of cold air (which is denser) getting trapped at ground-level under a cap of warm air. Although the two bodies of air are flipped over, the moisture is still at ground level — and now the body of cold air there is too, so clouds form around your feet.

That’s exactly what you see happening in the video above. It’s part of the Skyglow Project, a crowdfunded project that aims to explore the effects of urban light pollution by examining some of the darkest skies across North America. It was shot after a cool, rainy night on the Grand Canyon. Moisture got trapped and condensed in the canyon, filling it to the brim with a sea of clouds.

Because inversions are rare in an of themselves and the Grand Canyon is so dry usually, you can catch the fog-filled vistas here only once every several years.

Video credit to Skyglow Project. Still taken from video.

Why clouds don’t fall

cloud

Our day to day life puts us face to face with many very interesting natural phenomena, but the average person doesn’t try to understand them; if asked about some of the simplest things, most people would just laugh at such silly questions. However, some questions seem simple and dismissable until you consider them — after, those same smiles slowly inch away people realize the question is way more interesting than it seems.

For example, take a few moments and think about why clouds don’t fall. Seems to be quite an idiotic question, but it’s actually not. For example, let’s take a look at the clouds themselves. Clouds are made of droplets of water or frozen crystals, which are heavier than the air around them — so why don’t they fall?

If we want to solve this puzzle, we need to know some things. First of all, clouds are made of really small drops of water. These small drops have a harder time at falling than their heavier counterparts. As they fall, their motion generates friction with the air around them. Since they have smaller mass but not that less surface area, they have a harder time pushing down through the air than their heavier counterparts — think of them like tiny ice parachutes. Just like parachutes, they fall slowly but they still fall. Meaning there’s something else that has to be considered.that something else is wind. We think of

That something else is wind. We think of wind as going parallel with the ground, from one side of the globe to another. But wind can also blow in perpendicular to the ground, straight up, for example, in what is called an updraft. This type of wind that stops small drops from falling down.

But going a bit further from our question, one would assume that it’s possible for the drops to get bigger until the wind is not strong enough to keep them from falling. But even then, it wouldn’t be correct to say that the whole cloud falls at once, just as a big chunk of cheese would. The biggest drops fall first, followed by progressively smaller ones until there isn’t enough water left to form more drops. We know this as rain.

Jupiter's cloud bands extend hundreds of kilometers beneath the cloud deck. Credit: NASA/JPL-Caltech/SwRI/GSFC

Jupiter’s cloud bands extend for hundreds of kilometers into the atmosphere

Jupiter's cloud bands extend hundreds of kilometers beneath the cloud deck. Credit: NASA/JPL-Caltech/SwRI/GSFC

Jupiter’s cloud bands extend hundreds of kilometers beneath the cloud deck. Credit: NASA/JPL-Caltech/SwRI/GSFC

The fifth planet from the sun is famous for its multi-coloured bands that dot its atmosphere, making Jupiter resemble a marble. Until recently, no one was sure whether these stripes are only on the surface, like blemishes, or extended farther inward. Thanks to an unprecedented look inside Jupiter’s atmosphere by the Juno spacecraft, we now know these stripes reach at least 350 to 400 kilometers beneath the outermost halo.

Peeling Jupiter

These remarkable findings were made public last week by Scott Bolton, head of the Juno mission, at the American Astronomical Society’s Division for Planetary Sciences.

It took the Juno spacecraft five years to reach the massive planet, but it eventually entered its orbit on July 4. It soon after turned over a slew of gems like the first ever colour image of Jupiter from orbit, as well as valuable data. For instance, thanks to Juno, we now know why Jupiter’s atmosphere is so hot — because of its famous red spot.

Now, the same Juno probe peered through Jupiter’s clouds, which optical light can’t penetrate. Using microwave instruments that each probe the coloured stripes at different wavelengths, NASA scientists were able to distinguish between the various types of clouds, like peeling back the layers of an onion. The microwave data revealed a striking find: some of these stripes are still visible deep into the cloud.

“The structure of the zones and belts still exists deep down,” Bolton said during a news conference .”So whatever’s making those colors, whatever’s making those stripes, is still existing pretty far down into Jupiter. That came as a surprise to many of the scientists. We didn’t know if this was [just] skin-deep.”

“Deep down, Jupiter is similar but also very different than what we see on the surface,” Bolton added. “We can’t tell what all of it means yet, but it’s telling us hints about the deep dynamics and chemistry of Jupiter’s atmosphere.”

Interestingly enough, the bands from the top clouds are not identical to those seen in the subsequent layers, despite the similarities.

“They’re evolving. They’re not staying the same,” Bolton said. The finding “hints [at] the deep dynamics and the chemistry of Jupiter’s atmosphere. And this is the first time we’ve seen any giant planet atmosphere underneath its layers. So we’re learning about atmospheric dynamics at a very basic level.”

The microwave measurements were made during Juno’s flyby of Jupiter on August 27. The closest encounter between the gas giant and a man-made craft also returned other interesting findings. For instance, by measuring the magnetic field of the planet, NASA scientists found that Jupiter’s beautiful auroras are not unlike the northern and southern lights that flash in the polar skies on Earth — that’s despite that these are 100 times brighter than on Earth and stretch over a huge surface.

There is still much to learn about Jupiter and as long as Juno is still operational, we will learn more. Right now, the probe is on a non-circular orbit which takes 53 days to complete but will soon fire its engine to enter a 14-day orbit.

 

Climate change pushing clouds higher into the atmosphere, shifting them towards Earth’s poles

Climate change is pushing clouds higher into the atmosphere and causing them to shift towards the Earth’s poles, according to a new study.

Image credit Pexels

Image credit Pexels

A new analysis of various types of clouds records has revealed that the Earth’s clouds are being pushed higher into the atmosphere and moving towards its poles. The data points to the increase in atmospheric greenhouse gases caused by climate change as the culprit and aligns with the predictions made by previous climate models.

“What this paper brings to the table is the first credible demonstration that the cloud changes we expect from climate models and theory are currently happening,” said Joel Norris of the Scripps Institution of Oceanography at University of California San Diego and lead author of the study.

Understanding the behavior of clouds is important for climate scientists due to the unique roles that they play – in addition to cooling the planet by reflecting solar radiation, they are also responsible for trapping solar energy and heating the planet. This unique dual role is one of the biggest obstacles for climate scientists attempting to better understand how to curb global warming.

Most cloud imaging data is unreliable due to being captured by satellites designed to weather monitoring. These devices are prone to be influenced by changes in their orbit, calibration, and sensor degradation, among other factors.

Norris and his team removed these artifacts from several independent satellite records in order to get a clearer picture of cloud behavior and revealed their increasing height and movement towards the Earth’s poles.

The findings are concerning because these changes increase the absorption of solar radiation by the Earth and decrease the emission of thermal radiation to space, both of which contribute to the global warming that stems from the increase in atmospheric greenhouse gas concentrations witnessed in the recent years.

Journal Reference: Evidence for Climate Change in the Satellite Cloud Record. Published 8 July 2016. 10.1038/nature18273

NASA snaps beautiful picture of Mars as it inches over towards Earth

NASA astronomers captured a beautiful image of Mars on May 12, when the planet was just 50 million miles away from Earth. Bright snow-capped polar regions and rolling clouds above the rusty landscape show that Mars is a dynamic, seasonal planet, not an inert rock barreling through space.

This picture was taken just a few days before the Mars opposition on May 22, when the red planet and the sun will be on exact opposite side of the Earth. Mars circles around the sun on an elliptical orbit, and its approaches to Earth range from 35 to 63 million miles. From now to May 30 Mars will inch in ever closer to 46.8 million miles from us — the closest this planet has been to Earth for the last 11 years. Being illuminated directly by the sun, Mars is especially photogenic and NASA used this opportunity to capture a beautiful shot of the planet.

The most eye-catching features are the thick blankets of clouds, clinging to the planet’s thin atmosphere. They can be seen covering large parts of the planet, including the southern polar cap. The western limbs are early morning clouds and haze, while the eastern part is an afternoon cloud extending for more than 1,000 miles at mid-northern latitudes. The northern polar cap is barely visible, as it’s now late summer in that hemisphere.
Mars Near 2016 Oppostion (Annotated)

The overcast Syrtis Major Planitia is an ancient shield volcano, now inactive. It was one of the first structures charted on the planet’s surface by seventeenth century observers. Huygens used this feature as a reference point to calculate the rotation speed of Mars — one day on the red planet clocking in at 24 hours and 37 minutes.

Hellas Planitia basin extends to the south of Syrtis Major. At about 1,100 miles across and nearly five miles deep, you’d think it’s a tectonic depression, but it was actually formed 3.5 billion years ago when a huge asteroid crashed into Mars. The planet had its fair share of meteorite impacts throughout the ages, as Arabia Terra can attest — this 2,800 mile upland region is dotted with craters and heavily eroded. Dry river canyons wind through the region, testament to rivers that once flowed into the large northern lowlands.

The long, dark ridges running along the equator south of Arabia Terra, are known as Sinus Sabaeus (to the east, not pictured) and Sinus Meridiani (to the west). These areas are covered by dark bedrock and sand ground down from ancient lava flows and other volcanic features. The sand is coarser and less reflective than the fine dust enveloping the planet, making them stand out.

Several NASA Mars robotic missions, including Viking 1 (1976), Mars Pathfinder (1997) and the still-operating Opportunity Mars rover have landed on the hemisphere visible in this picture. Spirit and Curiosity Mars rovers landed on the opposite side of the planet.

All images provided by Hubble Site.

The Skypunch – not a fancy anime combat move, but just as awesome

It sounds like something Goku does when he’s having a really bad day, and looks a bit like a hole the mothership left after it passed through the clouds.

Image via reddit

Image via reddit

They’re round, spectacular, they’re freaky. One of the rarer cloud phenomena out there, Skypunches are also undeniably beautiful.

But what exactly are they, and how do they form?

“Skypunch” is the colloquial name of a phenomenon known as a Fallstreak hole – a large circular or elliptical gap that can appear in cirrocumulus or altocumulus clouds.

When the water vapors that form clouds are cooled below their freezing point, but they do not have a suitable nucleus -such as pollen, a dust or even volcanic ash particle- to adhere to and form ice crystals, they do not solidify. This is known as supercooling:

When the vapor is in supercooled state, all that it takes is for a few ice crystals to form setting off a domino effect, due to the Bergeron process, causing the water droplets around the crystals to evaporate: when this happens naturally, it leaves a large, circular hole in the cloud, centered around the area of first crystallization.

Image via pprune.com

Image via pprune.com

Image via mesosyn.com

Image via reddit

Elongated Fallstreak holes are associated with air traffic; ice crystals can be formed by passing aircraft which often have a large reduction in pressure behind the wing- or propeller-tips. This cools the air very quickly, and can produce a ribbon of ice crystals trailing in the aircraft’s wake.

Image via abc.net.au

Image via mytechnologyworld9.blogspot.com

So the next time you see a jet-trail on a particularly cloudy day, keep looking up. You might be lucky enough to see a Skypunch being delivered.

Researchers make Mars clouds on Earth

Researchers at MIT have recreated Mars-like conditions within a three-story-tall cloud chamber in Germany, adjusting the temperature and humidity to match those on Mars – basically creating Martian clouds.

mars clouds

Illustration via NASA.

Judging by the images Curiosity has sent us, Martian clouds look quite similar to ours – the gauzy, high-altitude wisps look a lot like the cirrus clouds we find here on Earth. Judging by what researchers know about Martian clouds, they are probably carbon dioxide or water-based ice crystals, though it’s hard to estimate the conditions which lead to their formation.

The first thing they noticed was the humidity – in order to create these clouds, they had to raise water humidity to 190 percent, far greater than cloud formation requires on Earth. The finding should help improve conventional models of the Martian atmosphere, many of which give Mars and Earth a similar humidity.

“A lot of atmospheric models for Mars are very simple,” says Dan Cziczo, the Victor P. Starr Associate Professor of Atmospheric Chemistry at MIT. “They have to make gross assumptions about how clouds form: As soon as it hits 100 percent humidity, boom, you get a cloud to form. But we found you need more to kick-start the process.”

In order to recreate the conditions, they the used Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility – a former nuclear reactor which is now being used in cloud studies. The building was initially used to study Earth clouds, but Cziczo realised that with just a little fine tuning, it could also be used for Martian clouds.

The AIDA facility.

The AIDA facility.

To do this, he first pumped all the oxygen out of the chamber, and instead filled it with inert nitrogen or carbon dioxide – which are omnipresent in the Martian atmosphere. Then they created a dust storm, of course, with the same minerals and grain sizes found on the Red Planet; this was a crucial step, because just like on our planet, these particles act as cloud seeds around which water vapor can adhere to form cloud particles. They then adjusted the temperature, trying out different temperatures commonly found on Mars as they went. By adjusting the chamber’s relative humidity under each temperature condition, the researchers were able to create clouds under warmer, Earth-like temperatures, at expected relative humidities, which gave them confidence that they are working with the right parameters as they moved on to colder, Martian temperatures.

During a week’s time, they created 10 clouds, with each cloud taking about 15 minutes to form. Since the room was perfectly insulated, they used a a system of lasers, which beam across the chamber, to detect cloud formation. Whenever clouds were formed, the light would be diffracted and this scattering is then detected and recorded by computers, which display the results – size, number and type of particles.

They plan to return next fall for even more experiments, going to lower temperatures, which are closer to the icy surface of Mars.

“If we want to understand where water goes and how it’s transported through the atmosphere on Mars, we have to understand cloud formation for that planet,” Cziczo says. “Hopefully this will move us toward the right direction.”