The radiation and convection zones describe how energy created in the core is being transported Grumpy cat rest in peace 2012 2019 shirt. In the radiation zone https://usat-shirt.com/grumpy-cat-rest-peace-2012-2019-shirt/, the heat is transported by atoms bouncing faster near the core, which propagates outwards. But if the energy gradient is too large, then one gets convection. In convection, packets of gas inside the Sun are heated so rapidly that they expand and become bouyant, and rise. The cooler gas in the outside falls, and one gets circulation. This is exactly equivalent to boiling water, except in this case it is (mostly) hydrogen and helium gas boiling instead of water.
Grumpy cat rest in peace 2012 2019 shirt, hoodie, sweater and tank top
Best Grumpy cat rest in peace 2012 2019 shirt
Fusion takes place in the core because of the very high Grumpy cat rest in peace 2012 2019 shirt. I am not sure why it has anything to do with quantum tunneling. The temperature in the core is well over a million degrees, and this is sufficient to fuse H into He via the proton-proton chain. In simple terms, the high temperature means that atoms are bouncing around faster and therefore will be more likely to run into each other and fuse.