How does elevation influence precipitation? The correlation between altitude and rainfall is an intriguing element of meteorological phenomena and environmental processes.
When air masses traverse varying altitudes, they come across alterations in atmospheric conditions, temperature, and pressure, which affects precipitation.
But, the question remains, “How does elevation affect precipitation in different conditions?”
Precipitation is affected by changes in air temperature and atmospheric conditions, both of which are influenced by elevation.
How Does Elevation Influence Precipitation?
Elevation can have an impact on precipitation patterns due to a change in atmospheric conditions, the formation of rain shadows, and so on.
Let’s discuss a bit more about it:
Relationship between Elevation and Atmospheric Conditions
All atmospheric conditions are governed by the air’s pressure, density and temperature.
However, the atmospheric conditions at sea level are vastly different from the conditions found at elevation, particularly at higher altitudes above 2,400ft.
The Changes in Air Pressure
The further away from sea level a location is the more the air pressure falls because there is less atmosphere above pressing down.
The air is also less dense, its humidity levels are lower because as it rises and expands it loses its gas molecules including oxygen, nitrogen, and carbon dioxide, to space and the atmosphere.
It also loses the heat they produced as they reacted with each other, making the air temperature colder.
The cold draw warm moisture out of the rising air columns to condense and form clouds of water vapor.
The differences in the rising air’s pressure and temperature create strong winds which combined with the low oxygen and cold temperatures make it difficult for life to thrive.
Fact: Higher elevations tend to have cooler temperatures, which can increase condensation and precipitation, and hence lower atmospheric stability.
Orographic Precipitation and Elevation
Orographic precipitation is produced when moist air rises to cool and form clouds.
The kind of precipitation these clouds produce depends on how low the temperature falls.
All precipitation is falling water but since water changes its state according to its temperature, where the temperature in the cloud is low, it falls as ice or snow.
Where the temperatures are higher, it falls into its liquid state as rain. The temperatures in clouds fluctuate constantly.
Therefore, a cloud often produces more than one kind of precipitation at once which in turn, is influenced by the various temperatures it encounters on the way down.
Mountains Affecting Precipitation Patterns
In physical geography, orography is the study of mountains and their effects; the orographic effect is one example.
It is an atmospheric condition triggered by air being forced upwards by elevated land, hills or mountain ranges.
The effect results in more rain falling in the mountains than on the plains as the air mass is forced to rise because of a phenomenon referred to as orographic lift.
As the air rises and its altitude increases, the cooler temperatures result in the water vapor condensing into orographic clouds.
The process is part of an orographic sequence that has a huge impact on the weather.
Fact: Due to lower temperatures and greater availability of moisture, snowfall tends to be heavier and more frequent in regions with a higher elevation.
Rain Shadows Impact on Precipitation
The topography of the land has a huge impact on where the precipitation falls and mountains act as barriers blocking and funneling moisture-heavy air currents.
Mountains produce a well-known effect, the rain shadow, on the leeward side of the range.
It results from warm moist air forced up and over the ranges to cool and drop orographic precipitation only on the windward side.
The leeward side of the range sees very little and is desert-like with sparse vegetation and arid conditions largely unconducive to life.
By contrast, the windward side with plenty of rain will have a diverse ecosystem.
Elevation and Temperature Causing Precipitation
As the air over the oceans is warmed by the sun, it rises, and the moving current of air pulls water vapor off the surface of the water, often carrying it for miles until it meets land.
Although water freezes at 0oC (32oF) even a slight rise or fall in the temperatures around it will trigger a change in its state.
Because temperatures higher up are so low, most precipitation begins life as snow as the warm air current is subjected to rapid cooling.
Each snowflake will only reach the ground as snow if the temperature stays at or very near freezing all the way down.
Although initially a snowflake, the liquid in a raindrop might change state several times as it falls through the atmosphere.
Conditions will never allow it to reform as a snowflake, so it falls as hail. When the temperature is greater than zero, it rains.
Fact: Elevated locations are more likely to experience convective processes and heavy precipitation as a result of atmospheric instability.
Elevation and Atmospheric Moisture Affecting Precipitation
By blocking clouds and taking the rain, mountain ranges impact the climate of the regions behind them.
When air reaches mountains, orographic lift forces it up into the colder atmosphere. The falling temperature also impacts the cloud’s humidity.
In the colder, thinning air finds it harder to retain the heat and the moisture it gathered over the ocean, and moisture precipitates out onto the windward side of the mountains.
It cannot be replaced by evaporation; the air is too cold to trigger the process and with increasing height the cloud loses most of its humidity and therefore its volume.
Consequently, there is less of it to make it over the summit to reach the mountain’s leeward side.
An Important Consideration
The air that does make it is significantly drier and although it quickly warms it contains very little moisture, most will have been wrung out and dumped during its ascent.
Fact: Increased moisture and precipitation may be a result of higher altitudes experiencing more frequent fog and low-level cloud cover.
Examples of Regions and Their Elevation Related Precipitation Patterns
There are several examples of how precipitation patterns change due to elevation in different regions.
For instance:
Mawsynram
There are locations on the windward sides of mountain ranges that experience some of the world’s highest annual rainfalls.
Mawsynram in the East Khasi Hills of India is described as the wettest rainiest place on the planet and typically enjoys a cool 20oC climate.
It lies in the path of the warm air rising in the Bay of Bengal and receives, on average 11,871mm of rain annually.
Cherrapunji
Cherrapunji, averaging 11,777mm and at 1484m elevation, lies just three hours east of Mawsynram and is at a similar elevation and backed by the Hills.
It means the two towns are in competition when it comes to determining who has received the highest annual rainfall on the Asian continent but also the world.
Columbia
Columbia is crossed by the Andes north to south, divided into three mountain ranges, the Cordilleras running parallel to the Pacific Ocean coast.
Its tallest peak, Pico Cristóbal Colón stands at 18,947ft but there are several others over 16,500ft.
Columbia’s climate is influenced by the Pacific’s cycle of warming and cooling, producing warmer and wetter El Niño and rainier but colder El Niña.
Under their influence annual rainfall has reached 8,000 mm, although around 25,500mm is more normal.
Importance of understanding elevation-related precipitation
Since 1961, global agricultural output has tripled as new land has been cultivated.
Even so, since then the amount of new land has only increased by 12%.
Although its impact was to lower the amount of land needed to support one human from 0.45 hectares to .0.22 hectares a year, it highlights how little land is available for mass cultivation.
Changing weather patterns are already impacting agriculture with intense rain occurring more frequently.
This results in the following:
- Faster topsoil erosion
- Flash flooding
- Coastal erosion
- Rainshadow droughts
The rise in sea levels will affect some of the world’s most fertile land, just as rising temperatures boost evaporation drying out the ground.
It is therefore vital to understand how elevation-related precipitation can be managed effectively to limit the impact of massive amounts of water running away from higher altitudes into swollen rivers to flood the plains.
Takeaway
How does elevation influence precipitation? The altitude has a notable impact on the precipitation trends.
The formation and distribution of precipitation are influenced by changes in temperature, pressure, and atmospheric conditions as air masses move up and down different elevations.
Through the analysis of these patterns, researchers and weather experts can enhance their ability to predict weather conditions, develop accurate climate models, and implement sustainable resource management strategies.
