Hulling and chopping strawberries and discovering perfect little hearts inside,.However, I seem to have started 4 pairs! It seems that in all aspects of life I'm in great need of some serious organising.Īnyway, here are some snippets from my summer. This always seems to happen to me during the hottest months of the year, I suppose it's a form of planning for cooler times. I finished a shawl and was also seized by the desire to start knitting mittens. Lots of knitting was done on the cooler summer days but it was haphazard, and I have little knitted body parts and scribbled notes scattered throughout the house. Once I've tidied my inbox I'll be starting pattern writing again. I'm now 'back at work' and have a large email backlog to work through - I'm so sorry if you're waiting on a reply from me, hopefully you'll receive one this week. ![]() He returned to college last monday and so I spent last week tidying the house, sorting laundry, and tackling all of the householdy things that were neglected during August. Caring for Toby 24/7 is intensive and full on and therefore not much else gets done. I ran out of steam a little in August, hence the lack of posts here. The land has soaked it up and quenched the parched plants and trees, and green has returned to the countryside all around us here, it is beautiful. It's been wonderful to feel it on my skin and to smell that unique scent that the arid land gives up after rain - isn't it brilliant that there's even a special word for it - petrichor. “Ultimately,” he says, “I would love to give meteorologists a simple formula that says, ‘if wind is of a certain magnitude, then rain will come in forty minutes’–but this is still a dream.The much longed for rain has at last come, and it's come, and come. “It points the right way towards the future.”įalkovich believes that the model may apply to other systems, such as fuel sprays in combustion engines and pollutant concentrations in the atmosphere, but his real hope is for the weather. “It’s a good piece of work,” Kadanoff says. Kadanoff says that in the past five years sophisticated analytic models like this one have been developed, but this paper is one of the first attempts to apply them. “This paper is a reflection of a long series of works on the motion of particles in flows,” says Leo Kadanoff of the University of Chicago. “In these dense clusters,” he says, “there is a much higher probability for them to collide and create bigger droplets.” According to the team’s new calculations, these clusters appear to be about a millimeter in size–just the size needed for raindrops to begin falling. These tiny vortices, according to Falkovich, act as centrifuges, spinning the micrometer-sized particles out to the edges, where they cluster together. The inside of a cloud is full of turbulence that creates many swirling eddies of air. Now Falkovich and his colleagues believe they may have found a key factor in the formation of raindrops: wind turbulence. ![]() But even after theorists included wind velocities in their models, they could not make their predictions match observation. The wind, it was believed, increased the relative velocities of the micrometer-sized droplets and caused them to collide and stick together until they became large enough to begin falling. Theorists have suspected for nearly forty years that wind was a catalyst helping the raindrops form more quickly. “And empirically people noticed that often rain starts long before this–say in half an hour.” “When you estimate the typical time you need to grow from micron- to millimeter-sized droplets, it would take maybe ten or fifteen hours,” says Gregory Falkovich of the Weizmann Institute of Science in Israel. Theorists and experimentalists understand this progression, but they cannot agree on how long it takes. ![]() As they fall, the droplets accumulate more and more moisture, until they become the large raindrops that we see here on the ground. The dust particles grow to millimeter-sized droplets, which are heavy enough to begin falling. Raindrops begin forming when water vapor condenses on micrometer-sized particles of dust floating in the atmosphere. ![]() This discovery may eventually help meteorologists predict storms with better accuracy. Inside clouds tiny vortices created by the wind spin water-sodden dust particles into clusters, where they meld to form raindrops, say the authors. A paper in the 26 March PRL sheds light on this cloudy subject by showing that wind turbulence can play a crucial role. ×Īlthough the TV weatherman can say where raindrops might fall, researchers still have difficulty explaining why they form. Swirling winds inside clouds may be one of the keys to quick formation of raindrops.
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