Question

In general terms, what are the differences among the fou desert classifications? How are moisture and temperature distributions used to differentiate these subtypes?

Short answer

Hot and dry deserts have high temperatures and low rainfall; semi-arid deserts have more moderate temperatures and slightly more rainfall; coastal deserts receive low rainfall, but additional moisture from fog and dew, with cooler winters and warm summers; cold deserts receive more precipitation, mostly as snow, with long, cold winters and short, moderately warm summers.

Step-by-step solution

Identifying the Four Desert Classifications

The four main desert classifications are: hot and dry deserts, semi-arid deserts, coastal deserts and cold deserts.

Outlining Characteristics of Hot and Dry Deserts

These deserts are characterized by high temperatures in summer and cooler temperatures in winter. They receive little rainfall, which tends to evaporate quickly due to the high temperatures.

Detailing Characteristics of Semi-Arid Deserts

Semi-arid deserts exhibit moderate temperatures and receive more rainfall than hot and dry deserts, but the moisture level is still low.

Discussing the Characteristics of Coastal Deserts

Coastal deserts generally have cool winters and warm summers. The rainfall is low, but fog and dew provide additional moisture.

Explaining Characteristics of Cold Deserts

Cold deserts have long, cold winters with snow, and short, moderately warm summers. They get more precipitation than other desert types, mostly in the form of snow.

Key concepts

Hot and Dry Deserts

Hot and dry deserts, often referred to as 'arid deserts,' are quintessential deserts with vast expanses of sand and dunes. These areas endure sweltering temperatures during the day and significantly cooler conditions at night. It's these extreme temperature fluctuations that are hallmarks of a hot and dry desert.

The scant rainfall that does occur tends to evaporate rapidly due to the intense solar radiation and high surface temperatures. The plants and animals of these deserts have adapted to survive these harsh conditions, often through conserving water and avoiding daytime heat. You might be familiar with the Saguaro cactus, a classic example of flora that has adapted brilliantly to this environment.

Semi-Arid Deserts

Moving onto semi-arid deserts, these landscapes are a degree more forgiving when it comes to temperature and rainfall. Sometimes called 'steppe deserts,' they feature grasslands and shrublands that do not receive a lot of precipitation, but certainly more than their hot and dry counterparts.

Despite the modest increase in rainfall, evaporation still plays a key role in this biome, often leaving the ground dry. Flora and fauna here have adapted to the slightly more moderate climate but still utilize strategies to minimize water loss. An example of a semi-arid region is the sagebrush steppe of the Great Basin in the United States.

Coastal Deserts

Coastal deserts are unique ecosystems that offer a cooler alternative to the stereotypical desert. Remarkably moderated by proximity to the ocean, they possess cool winters and warm summers. Unlike the more inland hot and dry deserts, coastal deserts benefit from marine influences: fog and dew provide much of the moisture needed by the plants and animals.

These forms of precipitation can sustain various forms of life that wouldn't thrive in the more extreme desert climates. The Atacama Desert in Chile is one of the driest places on Earth, yet it supports life due to fog, known locally as 'camanchaca,' rolling in from the Pacific Ocean.

Cold Deserts

On the other end of the spectrum lie the cold deserts. Cold deserts, such as the Gobi Desert in Asia, experience frigid winters with snowfall and brief, moderately warm summers. These deserts may receive more precipitation than other types, primarily through snow but it's still not much when it comes to sustaining vegetation or life.

The snow here acts as a slow-releasing form of moisture as it melts, allowing certain cold-tolerant plants to survive. Animals in these regions are well-adapted to the cold, often having thick coats and behaviors that allow them to navigate the snowy environment. Interestingly, temperature extremes between day and night are not as severe as in hot and dry deserts.