Why does semi arid climate exist?

How high is Brisbane QLD above sea level Show you sources please? Is the Atlantic Ocean in the southeast? What is the name of the swift warm current that flows northward along the East coast of the US? How does light limit the distribution of algae in the ocean? What grows in the canopy layer of the rainforest? Which Mount Everest climber said 'because it's there'? Would it be more difficult to breathe in the Sahara Desert or the top of Mount Everest and why? What is the river that runs though aberystwyth? Where is the least saltiest sea in the world? Where is the Bowles House Museum in Westminster Colorado located? What jobs did the fathers do at the mission? How much does it cost to enter Acadia National Park? How do you find the scale factor of the golden gate bridge? Where is the Pacific Northwest Truck Museum in Brooks Oregon located? What two cities are located along the James River? How cold is it at the top of the rocky mountains? What is the Closest white sand beach to Duncan OK? Who lived in the Tower of London? What sea does the River Wear flow in to? How does acid rain effects the rainforest?