earth science

[Guest clementzzz]

hey what i'm new and i have a question, convection currents happen in the asthenosphere and are powered by nuclear decay right? at least thats what my science text book said about convection currents, but there is no nuclear elements inside the earth so how nuclear decay powers convections currents with out having a nuclear element to irradiate nuclear decay?

[iglak]

no, convection currents can happen in many places.

when something gets hot, it expands and becomes less dense.

if it is less dense than it's surroundings, it will rise.

as it rises, it will cool down.

as it cools down, it will be pushed out of the way by the other hot bits that came up after it.

it, and the rest of the material, will then start to fall to fill the space that the rising bits left behind.

 

if you have heat directed at one spot in something, lets say water, then the water will rise up above that point, and fall down to the side of it. then it will go back to that point. this circular motion is a convection current.

[NavajoEverclear]

"always never oxymoronic"--- brilliant. That reminds me of something brilliant i heard the otherday . . . . i cant remember what it was. Maybe it also had something to do with oxymorons or similar phenomenon, how about this : repetititive redundance. ---- i know i must have the brain of an omeba to still think that's funny, i don't think that was IT anyway

[VendingMenace]

but there is no nuclear elements inside the earth

 

Here is where you go wrong. There are radioactive elements within the earth.

 

Actually, this was quite the mystery for some time. Not till just a while ago (sometime in this century) could people expalin why the earth was as warm as it was -- at least and be as old as it should be. Until people really understood that nulcear reactions occur, no one could understand how the earth could be billions of years old, yet not be a cold frozen rock. If there was no heat sorce, then earth should have long ago lost its heat to space. However, it turns out that there are enough radioactive materials in the earth, that they have helped out keeping the earth warm all this time. So, we see that the earth can be really really rediculously old and still be a nice temerate temerature.

 

At least i think i remember readgin this somewheres

[iglak]

NavajoEverclear said in post #3 :

"always never oxymoronic"--- brilliant.

thanks... although it's highly :offtopic:

actually, nothing in my sig is 100% oxymoronic, if you think about it.