Seven waterspouts align as lava from the Hawaiian volcano Kilauea pours into the ocean in this striking photo from photographer Bruce Omori. Like many waterspouts–and their landbound cousins dust devils–these vortices are driven by variations in temperature and moisture content. Near the ocean surface, air and water vapor heated by the lava create a warm, moist layer beneath cooler, dry air. As the warm air rises, other air is drawn in by the low pressure left behind. Any residual vorticity in the incoming air gets magnified by conservation of angular momentum, like a spinning ice skater pulling her arms in. This creates the vortices, which are made visible by entrained steam and/or moisture condensing from the rising air. (Photo credit: B. Omori, via HPOTD; submitted by jshoer)
I saw this post recently and it made me wonder what’s going on. If you look in the upper right of the frame as the camera submerges, you can see a little vortex of water whirring about. Even with the awesome power of the wave rolling forward a little tornado of water seems able to stably form. Any idea what causes this phenomenon?
Tel Aviv University physicist Eshel Ben Jacob studies one visually
stunning result of this phenomenon: the growth patterns bacteria form in
response to laboratory-imposes stresses. Ben Jacob subjects his
petri-dish colonies to such challenges as borderline starvation and
infusions of noxious chemicals, just the kinds of threats that
microorganisms must survive in nature. The colors and shading of his
images represent artistic license, but the underlying images are of
actual colonies of tens of billions of organisms.
In response to Septrin antibiotic, for example, colonies of Paenibacillus dedritiformis bacteria
secrete “come-hither” signals that cause their members to drawer closer
together and form large vortices. This increases the colony’s ability
to dilute the antibiotic with the lubricating fluid secreted by
individual microbes. By contrast, when faced with a sparcity of food,
the colony reorganizes into narrow, straight branches that maximize
contact with the limited nutrients in its environment.
From start to finish Soctopus’ Vorticity socks. Don’t mind any dog hair my papillon has been shedding like crazy lately. Also sorry for the shoddy pictures it is thundering and storming outside so no nice natural lighting -_-
Literature is full of descriptions of monstrous whirlpools like Charybdis, which threatens Homer’s Odysseus. While it’s not unusual to see a small free vortex in bodies of water, most people would chalk boat-swallowing maelstroms up to literary device. But it turns out that, while there may not be permanent Hollywood-style whirlpools, there are several places in the world where the local tides, currents, and topology combine to produce turbulence, dangerously vortical waters, and even standing vortices on a regular basis.
One example is the Corryvreckan, between the islands of Jura and Scarba off Scotland. In this narrow strait, Atlantic currents are funneled down a deep hole and then thrust upward by a pinnacle of rock that rises some 170 m to only 30 m below the surface. The swift waters and unusual topology produce strong turbulence near the surface and whirlpools pop up throughout the strait. Other “permanent” maelstroms, such as those in Norway and Japan, arise from tidal interactions with similar structures rising from the sea floor.
“The notion that reality is to be understood as a process is an ancient one, going back at least to Heraclitus, who said that “everything flows”. The best image of process is perhaps that of the flowing stream, whose substance is never the same. In this stream, one may see an ever-changing pattern of vortices, ripples, waves, splashes…which evidently have no independent existence as such.”
A crystal grid is a number of crystals arranged into a particular geometric form creating a particular energy field/beams or vortices of light. The simplest crystal grid is a triangle formed of three crystals. When you form a crystal grid, the crystals should be of equal strength and similar size. You can form a grid of any geometric shape or symbol—each carries its own symbolism and uses. You might leave your grid up for an hour, or for months—whatever feels right, only you can know how long this must take. You might time your gridwork to coincide with a powerful solar eclipse or new or full moon, or you might use seven days (or hours) to heal seven chakras.
Broadcast your desires to the Universe (as a part of your new moon ritual, for example) by placing a tarot/oracle card or written list in the center
Increase the power of your crystal or flower essences, medications, other crystals etc.
Create strong protective boundaries around you or your space
Clear and charge simple items, like a necklace or talisman
Make a grid under your bed to promote restful sleep or sexuality
Make a large crystal grid that encompasses your whole house (or room) to raise the vibration of your whole space
Use a plus sign or dollar sign shaped grid for prosperity intentions
Use a simple circle or the caduceus symbol for healing intentions, with the picture of the person in the middle, and stones placed on the area of healing in the picture
Make a large grid on your floor, then place your body in the center to accomplish a number of purposes (more on this later…)
If you ever feel like you have taken in too much energy afterward, try holding a grounding crystal, taking a salt bath, or walking in nature. Don’t forget to clear your crystals, and ask permission before conducting this sort of work (you will intuitively know if its a “yes” or “no”).
so, how is lift actually generated? i’ve been going through Anderson’s Introduction to Flight (6th Ed.) and while it offers the derivation of various equations very thoroughly, it barely touches on why lift is generated, or how camber contributes to the increase of C(L)
This is a really good question to ask. There are a lot of different explanations for lift out there (and some of the common ones are incorrect). The main thing to know is that a difference in pressure across the wing–low pressure over the top and higher pressure below–creates the net upward force we call lift. It’s when you ask why there’s a pressure difference across the wing that explanations tend to start diverging. To be clear, aerodynamicists don’t disagree about what produces lift - we just tend to argue about which physical explanation (as opposed to just doing the math) makes the most sense. So here are a couple of options:
Newton’s third law states that for every action there is an equal and opposite reaction. If you look at flow over an airfoil, air approaching the airfoil is angled upward, and the air leaving the aifoil is angled downward. In order to change the direction of the air’s flow, the airfoil must have exerted a downward force on the air. By Newton’s third law, this means the air also exerted an upward force–lift–on the airfoil.
The downward force a wing exerts on the air becomes especially obvious when you actually watch the air after a plane passes:
This one can be harder to understand. Circulation is a quantity related to vorticity, and it has to do with how the direction of velocity changes around a closed curve. Circulation creates lift (which I discuss in some more detail here.) How does an airfoil create circulation, though? When an airfoil starts at rest, there is no vorticity and no circulation. As you see in the video above, as soon as the airfoil moves, it generates a starting vortex. In order for the total circulation to remain zero, this means that the airfoil must carry with it a second, oppositely rotating vortex. For an airfoil moving right to left, that carried vortex will spin clockwise, imparting a larger velocity to air flowing over the top of the wing and slowing down the air that moves under the wing. From Bernoulli’s principle, we know that faster moving air has a lower pressure, so this explains why the air pressure is lower over the top of the wing.
Asymmetric Flow and Bernoulli’s Principle
There are two basic types of airfoils - symmetric ones (like the one in the first picture above) and asymmetric, or cambered, airfoils (like the one in the image immediately above this). Symmetric airfoils only generate lift when at an angle of attack. Otherwise, the flow around them is symmetric and there’s no pressure difference and no lift. Cambered airfoils, by virtue of their asymmetry, can generate lift at zero angle of attack. Their variations in curvature cause air flowing around them to experience different forces, which in turn causes differing pressures along the top and the bottom of the airfoil surface. A fluid particle that travels over the upper surface encounters a large radius of curvature, which strongly accelerates the fluid and creates fast, low-pressure flow. Air moving across the bottom surface experiences a lesser curvature, does not accelerate as much, and, therefore, remains slower and at a higher pressure compared to the upper surface.
The world’s most powerful artificial tornado is part of the Mercedes-Benz Museum in Stuttgart, Germany. Though popular enough with visitors that the staff will bring out smoke generators to make it visible, the tornado was not built as an attraction - It’s actually part of the building’s fire protection system. The modern open design of the museum meant that conventional smoke removal systems were inadequate. Instead vorticity is generated in the central lobby with 144 wall-mounted jets. The angular velocity created by the jets is strongest at the middle, in the vortex core, due to conservation of angular momentum - exactly the way a spinning ice skater speeds up by pulling his arms in. The core of the vortex is a low pressure area, which draws outside air toward it - this is how the tornado pulls in smoke when there is a fire. The fan on the ceiling provides the pressure draw necessary for the smoke to be pulled up and out of the building at a supposed rate of 4 tons per minute. See the tornado in action here. (Photo credit: Mercedes-Benz Passion; submitted by Ivan)
There’s an infamous supposition about drains swirling one way in the Northern Hemisphere and the other way in the Southern Hemisphere. Destin from Smarter Every Day and Derek from Veritasium have put the claim to the test with experiments on either side of the globe. First, go here and watch their synchronized videos side-by-side. (To synchronize, start the left video and pause it at the sync point. Then start the second video and unpause the first video when the second video hits the sync point.) I’ll wait here.
That was awesome, right?! The demonstration doesn’t work with toilets because they’re driven by the placement of jets around the circumference. And your bathtub doesn’t usually work either because any residual vorticity in the tub gets magnified by conservation of angular momentum as it drains. It’s like a spinning ice skater pulling their arms in; the rotation speeds up. So, to get around that problem, Destin and Derek let their pools sit for a day to damp out any motion before draining. At that point, the Coriolis effect is strong enough to cause the pools to rotate in opposite directions when drained. You may wonder why the effect is so slight for the pools when it’s pretty stark with hurricanes and cyclones. The answer is a matter of scale. The pools are perhaps 2 meters wide, which means that the difference in latitude across the the pool is very slight and therefore, the differential speed imparted by the Earth’s rotation is also very small. Because hurricanes and cyclones are much larger, they experience stronger influence from the Coriolis effect. (Image credits: Smarter Every Day/Veritasium; via It’s Okay To Be Smart)
Aiutami.. Sto con il mio ragazzo da tre anni, litighiamo sempre, sto spesso male. Ma io lo amo, e credimi non so che fare..
io credo che esistano due tipologie di litigi: quelli costruttivi e quelli distruttivi.
in un rapporto dovrebbero esistere solo questi costruttivi, quelli che -dopo aver discusso anche per ore- ti permettono di riprendere da dove vi eravate interrotti, quelli che si concludono con baci dolci e abbracci forti. i litigi distruttivi, per l'appunto, distruggono e basta e non servono a far altro che interrompere i rapporti, a lungo andare.
dopo tre anni, dal mio punto di vista, è normale discutere un po’ di più. magari nel corso del tempo delle cose sono cambiate. All'inizio è sempre tutto bellissimo, poi le cose iniziano a dover incastrarsi e quando si salta qualche casella si finisce per dover tornare indietro a colmarle. sai cosa? l'importante è non crollare nel vortice delle abitudini. Se c'è l'AMORE, c'è TUTTO.