There's an overall movement of air between the equator and poles that affects the Earth's climate, this movement is called Global Atmospheric Circulation.

Here's how it works:

• At the equator, the ground is intensely heated by the sun.
• This causes air to rise, creating low pressure. Air separates and moves towards the poles.
• When it reaches 30° north & south of the equator, air cools and sinks, causing a high pressure zone.
• As air sinks, it becomes warmer and drier with low rainfall. This is where deserts are found, on the Tropic of Cancer.
• When air is sinking, this is HIGH Pressure.
• When air is rising, this is LOW Pressure.