T-F Warm air rises over the equator area and descends over the poles. And do the N & S weather systems mix?

Question

Even factoring in the earths tilt which gives us the seasons and the rotational speed( about 1000mph) at the equator, giving us the westerlies, there may not be much mixing of the Northern and Southern hemispheres atmospheres.True?

Answer 1

There is mixing along the equator due to the subtropical high pressure areas from Hadley cells. This pressure difference is what gives rise to the Trade Winds. Because of the Coriolis Effect, the winds in the northern hemisphere blow from the northeast toward the equator (clockwise) and the winds from the southern hemisphere blow from the southeast toward the equator (counter-clockwise).

This is the point of mixing. These winds are seasonal (implying that significant mixing occurs in cycles) and contribute to monsoons and such.

Answer 2

This is actually a rather complex question with many answers, so I'll try and cover the important points.

1.) Just because the equator is warm does not mean that air is rising. When meteorologists talk about warm air rising, that air must be warm relative to the potential temperature of the air above it (potential temperature is the temperature the air would have if it were brought to the surface pressure). What does cause the equator to have a lot of rising air is that it receives the most direct sunlight, allowing the surface air to warm more quickly than the air above it, spawning thunderstorms, typically in late afternoon.

2.) Using the blanket statement "warm air rises over the equator and descends at the poles" is also not a very good statement. Air rises and falls almost everywhere on the globe, it's just the rate at which it does so changes. Every time you see a low pressure system in the northern/southern hemisphere, there is significant rising motion associated with in. Conversely, there is sinking motion associated with high pressure systems.

Personally, I'm not 100% sure about interaction between northern/southern hemisphere weather. My guess is it does occur, but it's not significant. Weather as we know it on Earth exists for one reason-to balance energy. If you have high temps in one place and low temps in another, weather attempts to erase that difference. Same goes for pressure.

I'd say the best statement about interactions between the equator and the poles would be one that describes warm (cold) air being transported poleward (equator ward) in terms of energy balance.

Answer 3

Air rises in the equatorial trough and air descends in the polar highs but it is not the same air. The air that rises at the equator sinks back to earth at the sub-tropical ridge and then flows back to the equator in the trade winds creating the hadley cell. The air that sinks at the poles rises along the polar front in high temperate latitudes. Another cell, the ferrel cell makes a circuit between the polar front and the sub-tropical ridge.This is all highly simplified of course.

There is little cross-equatorial flow but some does occur as the equatorial ridge moves north and south with the seasons. The northeast trades of the northern hemisphere become the northwest monsoon of the southern hemisphere and the southeast trades becone the southwest monsoon of the northern hemisphere.