Tag: infrared thermography

Jupiter in Many Lights
Sometimes the key to unraveling a mystery is to observe the phenomenon in different ways. That’s why researchers are increasingly taking advantage of multiple instruments simultaneously observing targets like Jupiter. Here we see the gas giant in three different types of light: infrared, visible, and ultraviolet. Infrared bands reveal the hot and cold regions of Jupiter’s clouds, allowing scientists to identify convective areas. Ultraviolet observations can reveal high-energy processes, like Jupiter’s auroras. And the colors revealed in visible light can give hints about chemical make-up in different regions. But to get a fuller picture, scientists compare all three modes — along with radio signal data from Juno — to understand topics like the planet’s lightning-filled storms. (Image credits: International Gemini Observatory/NOIRLab/NSF/AURA/NASA/ESA, M.H. Wong and I. de Pater (UC Berkeley) et al.; via Gizmodo)
August 24, 2021
Freezing Splats
In fluid physics, there’s often a tug of war between different effects. For droplets falling onto a surface colder than their freezing point, the hydrodynamics of impact, sudden heat transfer, and solidification processes all compete to determine how quickly and in what form droplets freeze.
The images above form a series based on changing the height from which the droplet falls. Each image is divided into two synchronized parts. On the left, we see a visible light, top-down view of the freezing droplet; on the right, we see an infrared view of freezing. As the height of impact increases, the shape of the frozen drop becomes more elaborate, moving from a flat splat with a small conical tip all the way to one with a concentric double-ring in its center. (Image and research credit: M. Hu et al.)
March 23, 2021
Jupiter in Infrared
This stunning new image of Jupiter in infrared is part of a data set combining measurements from ground- and space-based observatories. The glowing Jovian orb seen here is a composite of some of the sharpest images captured by the Gemini North Telescope’s Near-Infrared Imager from its perch on Mauna Kea. The brightest areas correspond to warmer temperatures over thinner, hazier clouds, whereas the dark areas mark towering, thick clouds.
The ground-based images — and observations from Hubble — were timed to coincide with passes from the Juno spacecraft. This combination of infrared, visible light, and radio wave observations gives scientists an unprecedented look at Jovian atmospheric processes. It revealed, for example, that lightning measured by Juno deep inside Jupiter’s atmosphere corresponded to convective storm cores visible to the other imagers. The combination of observations allowed the researchers to reconstruct the structure of these Jovian storms in a way that no single instrument could reveal. No doubt planetary scientists will learn lots more about Jovian convection from the data set. (Image credit: Jupiter – International Gemini Observatory/NOIRLab/NSF/AURA, M.H. Wong (UC Berkeley)/Gizmodo, illustration – NASA, ESA, M.H. Wong (UC Berkeley), and A. James and M.W. Carruthers (STScI); research credit: M. Wong et al.; via Gizmodo)
June 8, 2020
Getting Cold
Just as some chemical reactions produce heat, many chemical combinations absorb heat. In “Getting Cold,” the Beauty of Science team demonstrates this by showing endothermic processes in both visible and infrared light. Combinations that appear humdrum from our normal perspective suddenly become vibrant and interesting when we see the temperature variations accompanying them.
Evaporation is a good example. As humans, we sweat so that when our sweat evaporates off our skin, it takes heat away with it. Water (the main ingredient in sweat) isn’t the fastest evaporating liquid, however. Here it’s shown alongside ethyl acetate, a common ingredient in nail polish remover. And anyone who’s used nail polish remover is familiar with the chill it leaves behind as it evaporates. Just look how much colder and darker it is when evaporating! (Video and image credit: Beauty of Science)
October 3, 2019
Chemistry in Infrared
Many chemical reactions, and the flows that accompany them, are invisible to the human eye. But in infrared wavelengths those same events are vibrant and energetic. In this video from the Beauty of Science group, various chemical reactions are shown in visible and IR wavelengths, revealing very different perspectives on the same thing. Many of the reactions are exothermic, meaning that they produce heat as they occur. Because of this the thermal imaging shows where the most intense reaction is occurring at a given time. Other areas gradually darken as diffusion and flow move and dilute the heat energy released. (Video and image credit: Beauty of Science, source)
March 1, 2018
Staying Cool in the Outback
Daytime temperatures in the Australian outback can soar, creating a harsh environment for life. Red kangaroos use several methods to regulate their body temperature during the hottest part of the day. They shelter under trees to escape the sun, they dig away the solar-heated topsoil and flop down in cooler soil, and they lick their forearms. Like our wrists, kangaroo forearms have a network of blood vessels near the surface. As their saliva evaporates, it cools the skin and the blood vessels beneath it. Humans are cooled the same way when our sweat evaporates, but a more kangaroo-like trick for cooling off is running cold water over your wrists. (Video credit: BBC/Planet Earth)
April 7, 2017
Saturnian Clouds
It may look like an oil slick, but the photo above actually shows the clouds of Saturn. The false-color composite image reveals the gas giant in infrared, at wavelengths longer than those visible to the human eye. NASA uses this infrared photography to identify different chemical compositions in Saturn’s atmosphere based on how they reflect sunlight. You can see an example of how they construct these images here. This detail shot appears to show cloud bands of different compositions mixing. You can see hints of shear instabilities forming along the edges where the light and dark bands meet. (Image credit: NASA; via Gizmodo)
November 23, 2016
Volcanic Vortex
This infrared image shows a kilometer-high volcanic vortex swirling over the Bardarbunga eruption. The bright red at the bottom is lava escaping the fissure, whereas the yellow and white regions show rising hot gases. Although the vortex looks similar to a tornado, it is actually more like a dust devil or a so-called fire tornado. All three of these vortices are driven by a heat source near the ground that generates buoyant updrafts of air. As the hot gases rise, cooler air flows in to replace them. Any small vorticity in that ambient air gets amplified as it’s drawn to the center, the same way an ice skater spins faster when she pulls her arms in. With the right conditions, a vortex can form. Unlike a harmless dust devil, though, this vortex is likely filled with sulphur dioxide and volcanic ash and would pose a serious hazard to aviation. (Image credit: Nicarnica Aviation; source video; via io9)
September 18, 2014
Reader Question: Does Flow Viz Alter Flow?
gorbax asks:
I’ve been wondering for a while, actually, how do we know when the method of flow visualization doesn’t actually alter the flow of a fluid itself?
This is a great question and one that fluid dynamicists have to deal with all the time. Ideally, we’d love to measure everything we want from a flow at all points at all times without doing anything to affect it. In reality, however, that just doesn’t happen. Some measurement techniques are less intrusive than others, but just about everything risks having some effect. This raises two questions: 1) How small can we make that effect? and 2) Do we even care if we’re affecting the flow?
With regards to the first, the onus is typically on the experimentalist to show that whatever visualization technique he/she uses is not significantly affecting the flow. For something like particle image velocimetry, which requires seeding the flow with particles, this means selecting particles that follow the flow rather than changing it and considering carefully how and where to seed the flow such that any added vorticity from the injection does not alter the flow significantly. Checking for this can be done many ways, for example with comparisons to other measurement techniques (with and without seeding) or by comparing to simulation.
The second question–do we care?–is also a significant consideration. Because the purpose of flow visualization is often to get a qualitative feel for the flow field rather than quantitative information, it is often not a significant concern if there is some slight effect from the visualization technique. This can often be the case with smoke-wire and dye visualizations where we just want to see what’s going on.
Finally, there are some instances of flow visualization which are completely unobtrusive to the flow. Schlieren photography and infrared thermography are two examples. Both are optical techniques that act from a distance and take advantage of extant flow properties to make certain features visible. The real key is knowing what technique(s) will work for the flow you have and will give you the information you want. After that, it’s all about proper and thorough execution. (Photo credits: N. Vandenberge et al., T. Omer, M. Canals, P. Danehy et al., A. Wilkens et al., W. Saric et al.)
June 11, 2013