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kentish maid

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Posts posted by kentish maid

    Net Weather Springwatch

    in Space, Science & nature

    Posted

    I thought this might be an interesting and fun idea for us on NW. The idea was formed when out walking this afternoon in unbroken and warm Spring sunshine (even if there's an E'ly on the way).

    My first sightings for this Spring today are....

    ... Honeybees (lots of them)

    ... Tortoiseshell butterfly

    Both were seen near my house in Westbury.

    Feel free to add your own first sightings. Will these species be forced back into hibernation in the next week?

    chavs in shorts, flip flops and burberry t-shirts. lets hope we get a cold spell to kill em off, bl**dy pests lol :lol:

    The Global Conveyor Belt Thermohaline Circulation

    in Spring Weather Discussion

    Posted · Edited by kentish maid

    Ok so we know that the oceans are dominated by the global conveyor belt thermohaline circulation. And from my understanding this circulation comes up from the bay of biscay direction (I know it circulates the world) and then veers round to the south west and off to the caribbean and onwards for the rest of its journey.

    My question is the Gulf stream effectively runs through this circulation and carries on in our direction from the SW and then on and up over Scandanavia.

    So here comes the million dollar question - Why doesn't the circulation of the global conveyor belt shift this movement and take the gulf stream with it on its travel south westwards instead of allowing it to pass right through and onwards to northern Scandanavia?

    Is it simply because these two forces are working at different depths in the ocean and therefore do not affect one another?

    Snow Melt

    in Spring Weather Discussion

    Posted

    The most likely reason for this, Emma, is due to minute differences over the surface of the grass area. Although the surface lookes even and flat there will be small differences in grass length and small surface undulations, even on a bowling green like surface.

    When the snow falls there will be areas where the snow is in direct contact with the earth at the base of the grass stems and other areas where there is an insulating gap between the two as the snow is supported on the grass blades.

    If the ground is not frozen hard prior to the snowfall, the areas of snow in direct contact with the soil surface will begin to thaw slowly, as this process continues the snow will sink slightly in this area and this will alter the surface albedo, allowing this area to absorb slightly more solar insolation ( even if the sun is not shining) and thus accelerate the thawing process.

    If the ground is frozen hard beneath the snowfall there will be no thawing from beneath but the minor irregularities of the snow surface itself will result in small differences in albedo. Initially any differences in the rate of thaw due to these minor irregularites will be imperceptible but as time progresses those areas absorbing slightly more insolation will constantly thaw slightly more quickly than other areas until the effect becomes noticeable.

    Once a hole appears in the snow sheet, however small, there is a rapid increase in albedo around that area and the snow thaws very quickly in comparison to a n area with complete cover. A good example of this is to observe the effect of walking across a pristine snow cover on a lawn. Even if the footsteps do not penetrate through to the grass the rate of thawing around the steps will be much greater than that over the undisturbed area due to an increase in albedo; eventually this will result in a thawed track through an otherwise even cover of snow.

    The same is true of concrete, tarmac, shed roofs etc, it is the very minor irregularites of the surface or the snow and the surface beneath which result in an irregular rather of thawing.

    I've gone on a bit, hope this is some help.

    T.M

    No thats great. It has been on my mind for a while (sad i know) but that explains it really well, especially the footprints.

    Thanks

    Snow Melt

    in Spring Weather Discussion

    Posted

    How come snow melts on the ground at different rates?

    I have witnessed snow melting at different rates on a flat, equal patch of grass with no underground heating influences, yet areas of snow melt before others. why is this? Its also been the same on concrete and other material like shed roofs.

    I would have thought that as it lays level, it would melt at the same time???

    Anyone know why this would be?

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