Why doesn’t it rain in the desert? If you look out across a dry desert and ponder the lack of moisture there, you are not alone.
So many people wonder why it doesn’t rain in the desert.
The truth is that learning about this characteristic will help us unravel the mystery of these sun-scorched wastelands.
But, what are those meteorological secrets that veil some of the world’s most barren but interesting ecosystems? And why don’t deserts get rain?
It doesn’t rain in the desert because of its proximity to high-pressure zones, where dry, sinking air predominates and the region gets very little precipitation.
Do Some Deserts Get Severe Rains?
Sometimes, but rarely, it rains heavily in deserts. Cloudbursts produce intense rainfall and are a common cause of flash flooding in arid regions.
Arid, compacted soil and a lack of flora in a desert mean the land cannot handle a flood of that magnitude.
As a result, rainfall accumulates rapidly on the ground, leading to flooding. Desert flash floods are particularly dangerous and devastating.
They pose a threat to highways and bridges because of the debris they can carry and the soil they can erode.
An Important Consideration
The North American monsoon is responsible for bringing considerable summer rains to the North American deserts like the Mojave and Sonoran.
When warm, moist air from the Amazon Basin reaches the Atacama Desert in South America, it can cause extremely unusual but intense downpours.
Fact: Topography, seasonal weather patterns, and the migration of air masses are just a few of the elements that might affect the frequency and intensity of rainfall in the desert.
Why Doesn’t It Rain in the Desert?
It is the lack of yearly precipitation and the high rates of evaporation that define deserts.
The global distribution of precipitation is affected by a number of factors, including geography, weather, and climate, all of which contribute to the current drought.
Atmospheric Circulation Patterns
The distribution of precipitation is heavily influenced by the circulation patterns of the Earth’s atmosphere.
The equator is a low-pressure zone because warm air rises there. Rainfall is usually the heaviest near the equator because the air cools and condenses as it rises.
When this warm, humid air reaches the poles, it cools and sinks, creating high-pressure zones at about 30 degrees north and south.
Subtropical highs are areas of high atmospheric pressure, and the sinking, dry air in these regions prevents the production of clouds and rain.
Fact: Several of the world's largest deserts—the Sahara, the Arabian Peninsula, and the Kalahari—fall within subtropical high-pressure zones.
Topographical Barriers
The presence of a mountain range can serve as a natural barrier, preventing humid air from reaching lower elevations.
Mountain ranges force masses of moist air upward, where it can cool and condense into clouds and precipitation on the windward side of the range.
Orographic lifting causes intense precipitation in certain regions.
There is less chance of precipitation on the windward side of the mountains since the air cools and dries out as it descends.
Rain Shadow
The absence of rain on the leeward side of a mountain range causes the phenomenon known as a rain shadow.
Forcing air to climb over a mountain range causes it to cool and dry out, leading to precipitation on the leeward side.
There is less of a chance of precipitation on the windward side since the air is warmer and drier as it sinks.
It is because of this phenomenon that deserts in rain shadow zones, such as the Gobi Desert in Central Asia are so dry.
Fact: The Great Basin Desert and the Atacama Desert are two examples of deserts located in the rain shadow of surrounding mountain ranges.
Prevailing Wind Patterns
Both the distribution of precipitation and the establishment of deserts are susceptible to prevailing wind patterns.
Northeastern trade winds in the Northern Hemisphere and southeast trade winds in the Southern Hemisphere carry humid air from the ocean to the land.
The cool, dry air that is incapable of producing significant precipitation can arise when these winds blow over cold ocean currents, which can happen in some places.
Temperature Variations
The amount of precipitation a place receives may also be affected by the local temperature.
The capacity of warm air to hold moisture is greater than that of cold air.
As the air warms, it expands its capacity to hold water vapor, allowing it to carry more moisture inland from the sea.
On the other hand, when the air cools, it loses some of its ability to store moisture, leading to condensation and subsequent precipitation of water vapor.
High temperatures and low humidity in a desert’s climate create arid conditions because evaporation is so much more than precipitation.
Ocean Currents
The climate of neighboring land masses can be significantly influenced by ocean currents, which in turn affects the development and longevity of deserts.
Coastal deserts can emerge when chilly, dry air encounters cold ocean currents along the western coasts of continents.
This is because the air is unable to condense enough water to make precipitation.
For instance, the Namib and Atacama deserts’ dryness is exacerbated by the proximity of frigid ocean currents.
Continental Interiors
The interiors of continents, far from the tempering impact of seas, can likewise become deserts.
These continental deserts see dramatic seasonal shifts, from hot summers to freezing winters.
Arid conditions can develop in these areas because of the low humidity and the great distance from significant water sources.
Fact: You can find continental deserts in places like the United States' Great Basin and Mongolia's Gobi.
Inversion Layers
Temperature inversions happen when warm air rises and becomes stuck above cooler air near the ground; this happens in some desert regions.
By acting as a ceiling, this heated air stops the cooler air below from ascending and condensing into clouds.
Therefore, the ground below the inversion layer receives no or very little precipitation and continues to be dry.
Persistent inversion layers are widespread in deserts, such as Chile’s Atacama Desert, which contributes to the region’s extreme dryness.
Human Influence
Human actions can contribute to desertification, although natural forces play a larger role in desert development and maintenance.
Degradation of land due to overgrazing, tree cutting, and water usage can make it more vulnerable to drought.
These anthropogenic alterations can exacerbate the consequences of natural variables that limit precipitation, turning once fertile regions into deserts.
Implications of Not Raining in Deserts
Inadequate precipitation has far-reaching effects on desert ecosystems, touching on many facets of daily life there.
The absence of precipitation in deserts influences the environment and defines the survival tactics of the people there.
Adaptation Mechanisms of Flora and Fauna
Deserts have their own unique ecosystems, with plants and animals that have adapted to the extreme circumstances they face.
The cactus is a good example of how desert plants have adapted to arid conditions by developing water-saving techniques such as shorter roots, smaller leaves, and tissue water storage.
Animals living in deserts face similar challenges, such as a lack of water and dramatic temperature swings, but they have adapted.
It is usual for desert animals to be nocturnal, to conserve water by excreting waste in concentrated form, and to derive their water needs from the foods they eat.
For instance, camels can go for days without drinking water because they store fat in their humps.
Similarly, kangaroo rats get all the water they need from their food and use their kidneys in unique ways to conserve it.
Biodiversity and Ecosystem Resilience
Deserts are home to an impressive variety of plant and animal life despite their arid climate and scarcity of water.
However, changes in environmental conditions or human activities can easily disrupt this biodiversity.
Desert ecosystems are especially vulnerable to disruptions because of the scarce precipitation they receive.
Desert ecosystems and their ability to maintain life are particularly vulnerable to climate change because they can increase water scarcity and cause more frequent and severe droughts.
Takeaway
Why doesn’t it rain in the desert? Deserts are characterized by their lack of precipitation, which results from atmospheric dynamics, topography, and location.
Although drought is the norm in these regions, flash floods and other forms of extreme precipitation are a constant threat.
This variability exemplifies the intricate web of variables that determines desert precipitation.
