Arid climate

We explain what an arid climate is, and describe its characteristics and subtypes. In addition, we provide examples of plant and animal life in arid climate regions.

An arid climate is a type of climate characterized by precipitation of less than 30 inches (500 mm) a year. Temperatures are extremely variable, with some very hot arid regions and others with colder climates. Another distinctive feature is the high temperature range: due to scarce rainfall, the temperature range between day and night is usually very wide.

Arid climates cover approximately 35% of Earth's surface. They are found in vast territories of North America and Oceania, in the south of South America, in northern Africa, and in parts of Asia.

The plant and animal life that thrive in this type of climate are adapted to aridity and the scarcity of precipitation throughout much of the year. In addition, these areas are very sparsely populated compared to other regions, with many of them being virtually uninhabited.

• See also: Tropical climate

Characteristics of an arid climate

Arid climates have the following characteristics:

• Precipitation is scarce, with rainfall levels of less than 30 inches (500 mm) a year.
• The temperature range between day and night is high.
• The atmosphere has low humidity.
• Plant and animal life is scarce, with little diversity (species must have adaptations for the lack of water).
• Maximum temperatures can reach 104 °F (40 °C), and minimum temperatures can drop to 32 °F (0°C).
• It is widely distributed: covering more than 35% of Earth's surface, in large regions of North America, Africa, Oceania, and Asia.

Arid climate types

Under the Köppen climate classification, there are four subtypes of arid climate:

• Hot semi-arid climate. Also called "hot steppe", it has a mean annual temperature above 65 °F (18 °C). It is characterized by mild winters and very hot summers, with low precipitation levels between 18 and 31 inches (300 - 500 mm) a year. Vegetation and animals are adapted to the extreme heat and the lack of water.
• Cold semi-arid climate. It has similar characteristics to the hot semi-arid climate, but unlike it, it has a mean annual temperature of less than 65 °F (18 °C). Precipitation is also scarce, but temperatures are lower, with very cold winters and mild summers. Plants and animals are adapted to survive the lack of water and the low temperatures.
• Hot desert climate. Precipitation is less than 18 inches (300 mm) a year, with annual mean temperatures of over 65 °F (18 °C). It is characterized by mild winters and very hot summers, with temperatures that have reached the highest ever recorded on Earth. Plant and animal life is very scarce. Only a few animals and plants can thrive in these conditions, with adaptations to withstand the heat and total lack of water throughout the year.
• Cold desert climate. It shares characteristics with the hot desert climate, but unlike it, it has annual mean temperatures of less than 65 °F (18 °C). Rainfall is also scarce, but temperatures are lower, with very cold winters and mild summers. Plants and animals are adapted to withstand the lack of water and the low temperatures.

The Köppen climate classification is one of the most widely used systems for differentiating climate types. According to this classification, there are five major climate types: tropical, arid or dry, temperate, continental, and polar climates.

Distribution of arid climates

The distribution of arid climates on Earth is as follows:

• Hot semi-arid climate. It is found in Northern Mexico and the Southern United States, the easternmost portion of Brazil, and parts of Northern Argentina and Southern Paraguay in the Americas; in some areas of Central and Southern Africa, in countries including Namibia, Botswana, Nigeria, Sudan, Ethiopia, and Kenya; in large areas of India in Asia, and in northern Australia in Oceania.
• Cold semi-arid climate. It is found in vast areas of Central and Northern United States, and in Southern Argentina in the Americas; in some regions of Southern Africa, in countries including South Africa and Lesotho; in vast areas of Asia such as Iran, Afghanistan, Kazakhstan, Mongolia, and China, and in South Australia in Oceania.
• Hot desert climate. It is a very widespread climate on Earth's surface. It is found in areas of Northern Mexico and Southern United States in the Americas; in much of Northern Africa, in countries like Egypt, Libya, Sudan, Tunisia, Chad, Morocco, and Niger; in the Arabian Peninsula and other parts of Asia, in countries like Saudi Arabia, United Arab Emirates, Yemen, Oman, Iran, Iraq, and Pakistan; and in much of Central Australia in Oceania.
• Cold desert climate. It is found in the Altiplano region in the south of South America, in some areas of Southern Africa, mainly in South Africa, and in the Himalayan Region in Asia, in countries like Kazakhstan, Kyrgyzstan, Nepal, China, and Mongolia.

Flora and fauna of arid climates

Plants in arid climate regions have adaptations to survive the scarcity of water. Some have very small leaves or thorns instead of leaves, which help reduce water loss through evaporation and better capture moisture from the atmosphere. Other plants have very long roots, which allow them to search for underground water. Cacti, such as the saguaro cactus or the cardon, are examples of this type of vegetation.

As for animal life, this climate is home to species that have developed adaptations to thrive in arid climates. Some animals are nocturnal to avoid the heat of the day, while others have the ability to store water in their bodies, allowing them to survive long periods without drinking. Typical species of these types of environments are camels, a wide variety of rodents, insects, and snakes.

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References

• Meteorología en red (s.f) Clima árido. https://www.meteorologiaenred.com/
• Sanz, I. (s.f) Clima árido: características, temperatura y precipitaciones. https://www.clima.com/
• Terrasa, D. (2018) Clasificación climática de Köppen. https://geografia.laguia2000.com/