Deserts: Characteristics

 

Deserts are regions of the Earth that receive very little rainfall, usually less than 250 mm per year. They cover about one-fifth of the land surface and can be hot or cold, depending on their location and climate. Deserts are characterized by extreme temperatures, low humidity, sparse vegetation, and high evaporation rates.

Deserts are not lifeless wastelands, however. They are home to a variety of plants and animals that have been attuned to the harsh conditions. Some of these specializations include drought tolerance, water conservation, heat tolerance, camouflage, and nocturnal activity. Deserts also have unique geological features, such as sand dunes, salt flats, oases, and rock formations.

Deserts are important for many reasons. They provide natural resources, such as minerals, oil, and solar energy. They also influence the global climate by reflecting solar radiation and creating wind patterns. Deserts are also rich in cultural diversity and history, as many civilizations have emerged and thrived in these environments.

Characteristics of Deserts

Deserts are fascinating ecosystems that cover about one-third of the Earth's land surface. They are defined as areas that receive no more than 25 centimeters (10 inches) of precipitation a year. Deserts are home to a variety of plants and animals that have adapted to the harsh and dry conditions. Below are some of the general characteristics of deserts and how they differ from other biomes.

            Aridity

The most obvious characteristic of deserts is their lack of water. Aridity is a measure of how dry an area is, based on the ratio of precipitation to potential evaporation. Potential evaporation is the amount of water that would evaporate from the surface if it were available. Deserts have a very low aridity index, meaning that they receive much less precipitation than they could potentially lose to evaporation. Aridity can be caused by various factors, such as distance from the ocean, rain shadow effect, cold ocean currents, or high atmospheric pressure.

            Temperature

Deserts are often associated with high temperatures, but this is not always the case. Temperature in deserts varies widely depending on the location, season, and time of day. Some deserts are hot and dry, such as the Sahara and the Arabian deserts, where daytime temperatures can reach up to 54°C (130°F) in summer. Other deserts are semi-arid, coastal, or cold, such as the Great Basin and the Gobi deserts, where winter temperatures can drop below freezing. Deserts also experience large diurnal temperature ranges, meaning that there is a big difference between day and night temperatures. This is because the dry air and sparse cloud cover allow more solar radiation to reach the ground during the day and more heat to escape to space at night.

            Humidity

Humidity is a measure of how much water vapor is in the air. Deserts have very low humidity levels, usually below 30%. Low humidity means that the air can hold more water vapor before it becomes saturated. This makes it harder for clouds to form and for precipitation to occur. Low humidity also affects the living organisms in deserts, as they lose more water through evaporation from their bodies and need to conserve water in various ways.

            Precipitation

Precipitation is any form of water that falls from the sky, such as rain, snow, hail, or fog. Deserts receive very little precipitation, usually less than 25 centimeters (10 inches) per year. However, precipitation in deserts is not evenly distributed throughout the year or across different regions. Some deserts may have seasonal rains, such as the monsoon rains in the Thar desert or the winter rains in the Atacama desert. Some deserts may have occasional flash floods, such as the Mojave desert or the Namib desert. Some deserts may have fog or dew, such as the coastal deserts along the Pacific and Atlantic oceans.

            Drought

Drought is a prolonged period of abnormally low precipitation that causes a shortage of water for human and natural systems. Droughts can occur in any biome, but they are more frequent and severe in deserts. Droughts can have negative impacts on agriculture, wildlife, health, economy, and society. Droughts can be classified into four types: meteorological drought (lack of precipitation), hydrological drought (low water levels in rivers, lakes, reservoirs), agricultural drought (low soil moisture), and socioeconomic drought (insufficient water supply for human needs).

            Wind

Wind is the movement of air caused by differences in air pressure. Wind can affect the climate and landscape of deserts in various ways. Wind can increase evaporation and reduce humidity by carrying away water vapor from the surface. Wind can also erode and transport sand and dust particles, creating landforms such as dunes, yardangs, and loess deposits. Wind can also influence the distribution of seeds, pollen, and spores of plants and fungi.

            Vegetation

Vegetation is the term used to describe the plants that grow in a certain area. Vegetation in deserts is sparse and adapted to survive in dry conditions. Some of the common specializations of desert plants are:

        - Reduced leaf size: to reduce water loss through transpiration

        - Thick cuticle: to prevent water loss through evaporation

        - Spines or hairs: to reflect sunlight and reduce heat absorption

        - Deep or wide roots: to access water from underground or nearby sources

        - Succulence: to store water in stems or leaves

      - CAM *** (Crassulacean acid Metabolism) photosynthesis: to fix carbon dioxide at night and reduce.

***CAM photosynthesis is a type of carbon fixation that some plants use in dry environments. It allows them to take in carbon dioxide at night and store it as an acid, which they can use for photosynthesis during the day without losing water.