how do mountains affect climate?

Answer 1

Climate is by definition the average of weather conditions over a regional area and over several years, ten years for example. So if mountains affect climate that means they have to affect weather over a reasonably long period of time and over a wide area.

A major effect mountains have is to lift air as the currents skim along the ground. As the air lifts, it cools. As it cools, moisture condenses out to form clouds. As the clouds gather, they are no longer able to hold the moisture and it rains or snows.

Thus, by the time the air currents cross over to the leeward side of the mountain, they are drained of moisture. When this happens over long periods and large areas, the dryness causes deserts to form.

Even if the air currents are not raised to pass over the tops, mountain ranges can keep the currents from going any further. In the San Francisco Bay area, for example, winds coming through the Golden Gate are stopped by the foothills on the East Bay side.

Thus, not only are the winds generally calmer on the leeward side of the foothills, but the temperatures are more extreme on that leeward side. This comes from the fact that the ocean temperatures moderate the air temperatures. Thus, in the winter, when the ocean is warmer than the air, the temperatures on the windward side are kept warmer than the air on the leeward side.

And, in the summer, when the ocean is colder than the air, the windward side is kept cooler than the air on the leeward side. As this happens year in and year out, mini climate areas are created where the climate on the windward side is quite a bit different from the leeward side.

Finally, mountain ranges generally alter wind patterns. So the winds that would naturally travel from west to east, are diverted on average so they travel more north west to sout east than straight west to east. Bottom line, mountains have major effects on climate.

Good question.

Answer 2

The old professor says: Mountains are a tremendous influence on world climates. Perhaps the most notable effect are the "rain shadow" deserts that are formed on the leeward side of mountain ranges. Warm humid air is forced up over the mountains. The air cools with altitude and the dewpoint is reached. The cool air becomes dry after the precipitation of moisture from it. As it descends on the other side of the mountain it warms up. This makes the relative humidity much less and so a desert is the result.

Mountains are high and therefore the air temps there are going to be cooler. Mountain tops have micro-climates which are normally cool and wet with either rain or snow.

Volcanic mountains can spew much dust into the atmosphere. In areas of long duration volcanism, the climate can be changed because of the increased precipitation due to an abundance of hydro- and hygroscopic nuclei for raindrops to form on. The temps can also be cooler due to the sun being obscured by the volcanic plume.

Mountains also can cause wind patterns that effect the climates in certain parts of the world. Consider the Santa Anna winds of California or the Chinook winds of New Mexico. These winds can carry air of different humidity and/or temperature to areas that would not otherwise be exposed to such variables.

Mountain caused weather and climate conditions are said to be orographic in nature.

Answer 3

When air that is saturated with water encounters a mountain, it is forced to rise, which causes it to cool. Cool air holds less water than warm air. The water falls as rain on one side of the mountain, depriving the other side of the mountain of moisture. Deserts are usually on the leeward side of mountain ranges. Rain forests are usually on the windward side of mountains.