Star brightness is defined by either <span>D. apparent magnitude - when we measure it from Earth (that is how bright it is from Earth) - this is the closest to "basic observation" and the best answer
or by absolute magnitute - how bright it would be at a certain distance (this allows to compare the brightness).
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Answer:
Ok so i will try my best to describe the answers:
1) a convection current is like a boiling pot of soup. the burner heats up the soup on the bottom. hot air always goes up because the molecules become more active, making them space out upward. the hot soup travels up through the center of the pot, and the cold soup up top travels down towards the edges of the pot to replace the hot soup that just moved up. the process keeps on going and going until there is no more heat, or until the burner turns off.
2&3) the sun makes everything warmer, so when the sun touches Earth's surface, it warms up the air around it. as soon as the air warms up, it goes up into the atmosphere, like the pot of soup example. then, cold air from the top moves in to replace the hot air. with so many molecules of air moving at one time, it makes gusts of wind during the movement. when it is really windy, that means that there is a lot of hot air moving up and cold air moving down. when there is no wind, that means that every molecule is where it is supposed to be, not disturbing one another.
I hope this helps :D
Is there a certian food chain they would like u to look at?
