Some geologists hypothesize that the mass extinction of dinosaurs was caused by a large meteorite impact. these geologists think the meteorite impact significantly changed earth's climate. how could a meteorite impact do this?

The meteorite was probably 10 to 15 km (6.2 to 9.3 mi) wide and affected the entire planet through a proces called "impact winter". As the name suggests, an impact winter is a period of low temperature produced by a huge cloud of ash and dust that blocks sunlight. Since sunlight is essential for plants to survive, if the sun rays are blocked by this cloud, all animals that depend on those plants (including dinosaurs) will die. The meteorite could have created such a cloud upon hitting the earth.