Why are cities in the mountains colder than cities at lower elevations?

As altitude rises, air pressure drops

Explanation:

Thin air exerts less pressure than air at a lower altitude. High-altitude locations are usually much colder than areas closer to sea level. This is due to the low air pressure.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.