Have you ever wondered why it’s colder the higher you go, even though you’re technically closer to the sun? It might seem logical to think that being nearer to the sun would make it warmer, but that’s not how it works on Earth. Even though I’m naturally curious about … everything, I’d never actually considered this question or the science behind it until a friend brought the topic up. And then, of course, I had to know the actual, science-based answer.
How Solar Radiation Interacts with Earth’s Atmosphere
The sun sends energy to Earth as solar radiation, including visible light and other types of electromagnetic waves. This energy warms our planet by interacting with the atmosphere. The important thing to remember is that the warmth we feel isn’t direct heat from the sun but comes from solar radiation absorbed and re-emitted by Earth’s surface and atmosphere.
For example, even though Mount Everest stands about 8,849 meters (29,032 feet) above sea level, this height is tiny compared to the sun’s distance from Earth, which is around 151.88 million kilometers (93 million miles). So, being a bit closer to the sun at higher altitudes doesn’t make much difference in temperature.
Atmospheric Pressure’s Role in Temperature
The main reason higher places are colder is because of the thinner atmosphere. At sea level, the atmosphere is dense, meaning there are more air molecules to trap and hold heat. As you climb higher, the air pressure drops because there’s less air above pressing down. For instance, the air pressure on Everest is about one-third of what it is at sea level, although it changes with the weather.
When air heats up, it expands and becomes less dense, causing it to rise. But as it rises and the pressure decreases, it expands even more, which cools the air down. This cooling process is known as adiabatic cooling.
What Is Adiabatic Cooling?
Adiabatic cooling is why higher elevations are cooler. When air moves from a low elevation to a high elevation, it expands due to the lower pressure. As it expands, its temperature drops.
NASA explains this well: “Higher elevations are cooler than lower elevations because of adiabatic heating. When a parcel of air moves from a low elevation to a high elevation, it expands because it is under less pressure. It has less weight pressing down on it from the air above it. As the air expands, its temperature drops.”
Effects on Weather and Precipitation
The colder temperatures at higher altitudes greatly influence weather patterns. When the air gets cold enough, precipitation turns to snow instead of rain. This is why mountaintops are often snowy. The cold air not only chills the ground but also helps snow build up instead of melting away.
In conclusion, the chillier temperatures at higher altitudes are mainly due to lower atmospheric pressure, which leads to adiabatic cooling. This explains why mountain peaks stay cold and snowy despite being closer to the sun.
