Ok thanks. That all makes sense. But why do they open/close if they're essential be be kept open? Which do I close to lower the temperature?
And does the same principal of iced water work with my Lambrini?
Thicker cuts of meat requires different treatment from say slices of steak. A streak can be cooked on pure radiation (heat supplied from the underside) because the radiated heat will penetrate say, 6mm into the meat before the outside layer is scorched black. Then you turn it over and do the other side, giving you 12mm off cookedness - which is enough to make the steak eatable without dripping blood. If the meat is 100mm thick, the radiated heat will still only penetrate 6mm per side before the outside is completely black. This leaves you with 88mm of uncooked heat.
Now, if you close the lid, the combustion is slower but the heat circulates around the meat (there is come convection and turbulence inside the dome lid before the heat eventually escapes through the top vent, just like in an oven). The lower heat from all sides gives the heat time to penetrate inside the meat without scorching the outside. Remember, meat is a heat insulator and heat travels slowly through it. The lower the heat, the better it will penetrate over time giving a more even cook. By closing the lid you are restricting combustion and the temperature reaching the meat is lower than by pure radiation when the coals are really fired from a free supply of oxygen.
Thus the rule of thumb is: For thin cuts, flash grill it in an open kettle. For thick cuts, close the lid for a more even but slower cook. Chicken requires the latter because chicken meat is very dense and an excellent insulator. It can therefore almost never be cooked on a grill alone without really searing the outside. Jut biting into a chicken breast will confirm its density. It can be grilled if you say slice the breast into two thinner "steaks."
Now, about that Lambrini. always thought it was a car, but anyway. If you have a bucket of ice water (i.e. lots of ice cubes and lots of water) as apposed to just a bucket of ice, your Lambor...Lambrini will go colder quicker and reach a lower temperature. This is for two reasons. When it is plonked into a bucket of ice cubes, on a few points of contact between ice and bottle is made. The cubes by definition cannot embrace the bottle. It can only touch it here and there. Ice water on the other hand, completely embraces the bottle, more contact is made and more heat travels from the bottle into the ice, making the bottle colder.
Further, and this is the strange one to non-chemists, ice water is colder than ice. In other words, if you put ice into water, the resulting slush will be colder than the ice itself. This is because energy is required to break up the ice's structure - which is what happens when it melts - and that energy is sucked from outside the ice, making the water colder than the ice itself. The converse, when water is frozen to become ice, is also true.
Next lesson - how to start the lawnmower so you can BBQ and sip Lambrini on a perfect lawn even when the chef and gardener is on vacation.