Discussion in 'Science and Technology' started by TrippinBTM, Jan 22, 2005.

  1. TrippinBTM

    TrippinBTM Ramblin' Man

    Why is December 21/the winter solstice the beginning of winter? Shouldn't it be the middle? It's the shortest day, we get the least why isn't it the colder time of the year? Why does it only get cold later, and stay cold right up till the spring equinox. This doesn't seem to make logical sense.
  2. katherine

    katherine Member

    Even though on the shortest day, the amount of heat from the sun is lowest, their is still a lot of heat left in the earth, since it is a very good store of heat (rocks, water and the air all store heat). Once this heat has gone, thats when temperatures reach their lowest. The same happens in the summer. 21st June is the longest day, so heat from the sun is highest, yet the earth has not yet warmed up yet, and it is not until late July/early august that temperatures peak. The sea is a particular good store of heat, which is why it would be much nicer to go swimming on 21st September than 21st March. Here in the UK our weather is effected quite a bit by this. For a start, the summer and winter both tend to be shifted back a bit due to the heating/cooling effect of the sea. Also, Spring tends to be very wet due to the warm land causing air to rise, sucking wet air in off the sea, but on the other hand Autumn (Fall) tends to be quite dry do to the warm sea sucking air off the land. All coastal areas get this effect, but it is felt more on islands due to being surrounded by water.
    Hope this helps clear it up. If so my Geography will have proved useful for something.
  3. shaggie

    shaggie Senior Member

  4. fat_tony

    fat_tony Member

    Despite the fact that we dont seem to have had a minter this year. My entire stunning cold weather wardrobe has been indefinately mothballed. That aside there is a natural delay as katherine noted. Id just like to add to her point about water, the jetstreams, high velocity winds high above the surface of the earth circulate in the temperate latitudes. They're part of the reason for the huge differences in flight time from London to New York, depending on which way you are going. These move north and south throughout the year. If they are to the north then you will get weather predominatly controlled by the golf stream (if you livein the UK). In the west US id guess its some kind of continental wind form the plains. In the winter these jetstreams migrate south, and temperate climates become dominated by polar winds. The winds take time to move for much the same reasons katherine gave.
  5. TrippinBTM

    TrippinBTM Ramblin' Man

    Hah, I beg to differ, and so does the foot of snow, blowing winds, and 2 degrees F! :p

    Anyways, your explaination makes sense, I didn't think about the heat-holding abilities of the earth, as I should have. Another mystery solved!
  6. fat_tony

    fat_tony Member

    apparently I should go to Detroit for christmas then
  7. I should be somewhat a bit of an expert on this. The sea temperature changes very slowly. However the air temperature does vary wildly. What a lot of people don't realise that most of the heat we do get is actually from our atmosphere. Without the atmosphere the poles would be much colder and the tropical regions will be much hotter. The energy imbalance is leveled out by the global circulation and by storms. But it is not totally balanced.

    I hate teachers that do that. they are basically to lazy to teach properly. Unfortunatly there are too many. So as a net result we get people coming out of school with crazy ideas. If you believe this then you should think about what is wrong with it. This is not ment to be an attack on you katherine but your teacher may of been over simplifying things a bit too much. You do get wild weather during the late autumn, winter and spring months. This is not due to the cooling and warming of the land though. Not on a small scale anyway. It is more down to the temperature contrast between the poles and the tropics. In the winter you get a larger contrast and more energy is needed to be shifted to the poles via storms and such like. Where as in the summer this contrast is not so much. Hence why winter is usually miserable and summer is nice. Autumn is probably nicer because there is less energy to transport as it is only just cooling down.
    I think you should do a bit of research on air masses a good starting point is this.

  8. fat_tony

    fat_tony Member

    Im puzzuled, so im not sure if this is a statement or a question. I havent done geo for a while outside of case studies in physics. But while I agree that large tempertaure changes are in the air while sea temperature varies only slightly, isnt the sea the driving engine for this. After all the sea has a much greater ability to absorb energy than the air. As I understood it arent those cells (Hadley and whatever) powered by gradients in sea temperature, while carrying air. I may be under a misconception but I always assumed that as these cells were driven by sea temperatures the delay for the peak of summer and winter was due to cooling and warming times of the sea.
    Also why are jetstreams sinusoidal with respect to lines of latitude as opposed to parallel to, thats another thing ive always wondered.
  9. I was rushing my last comment a bit. I forgot to mention about the sea being an influence on the three cell model. I guess you are probably right fat_tony. The sea does have a profound impact on the atmosphere but not all of it. Only the troposphere which incidentally is where all our weather is.

    Jetstreams are like that because of the gradient temperature which is vital for their existance and the fact that the earth spins. There is an experiment you can do to demonstrate it. You have a dishpan which is on a rotating table and filled with water. There is a heater on the outside edge of the pan to simulate the equator. In the middle you have a cooling cylinder. You then add a dye to the water. Preferably on the outside so you can watch it travel to the middle. You will get interesting wave patterns.

    Disclaimer: I will not be made liable if you decide to do this experiment and you end up hurting yourselves or damaging any equipment. That would be your own stupid fault.

  10. shaggie

    shaggie Senior Member

  11. xaosflux

    xaosflux Sysop Lifetime Supporter

    There are definantly religious links to the changing of the seasons, the winter solstice is often listed as the rebirth of the sun (they days stop getting shorter after it) by many old religions.
  12. EllisDTripp

    EllisDTripp Green Secessionist

    Yep. And the Xtians just co-opted the existing Pagan celebrations of solstices and equinoxes by grafting new symbolism onto them. The "rebirth of the sun" became the "Birth of the Son", just as the fertility rites of Ostara (Spring equinox) were morphed into "Easter". Ever wonder how a "Christian" holiday came to be celebrated on the first Sunday after the first full moon after the spring equinox? :)
  13. shaggie

    shaggie Senior Member

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