Question

Name three deserts that are visible on the classic view of Earth from space. Briefly explain why these regions are so dry. Can you also explain the cause of the band of clouds in the region of the equator?

Short answer

The Sahara, Arabian, and Gobi deserts are seen from space. Deserts are dry due to subtropical high pressure and geographic location. Clouds near the equator form in the ITCZ due to converging winds.

Step-by-step solution

Identify Deserts

Three major deserts that are visible on the classic view of Earth from space are the Sahara Desert in Africa, the Arabian Desert in the Middle East, and the Gobi Desert in Asia.

Explain Why Deserts Are Dry

Deserts are dry primarily due to their geographic location and atmospheric conditions. The Sahara and Arabian Deserts are dry because of the subtropical high-pressure zones creating stable air and minimal precipitation. The Gobi Desert's dryness is due to its inland position, far from oceans and moisture sources. All these factors limit cloud formation and rainfall.

Explain Equator's Cloud Band

The band of clouds near the equator is due to the Intertropical Convergence Zone (ITCZ). Warm air rises at the equator, where trade winds from both hemispheres meet. This rising air cools and condenses, forming thick clouds and frequent precipitation, creating a band of clouds visible from space.

Key concepts

Sahara Desert

The Sahara Desert is the largest hot desert in the world, sprawling over 9 million square kilometers across North Africa. Its immense size makes it highly visible from space. The Sahara is renowned for its vast stretches of sand dunes, barren rocky plateaus, and scarce vegetation.
The dryness of the Sahara is primarily attributed to its location in a subtropical high-pressure zone, where descending air causes evaporation to exceed precipitation. This zone discourages cloud formation, ensuring the desert remains arid. Moreover, the surrounding geographical features like mountain ranges block moist air and further accentuate its dryness.

Arabian Desert

The Arabian Desert lies on the Arabian Peninsula in the Middle East, spanning several countries including Saudi Arabia, Oman, and the UAE. This desert is characterized by a combination of sand plains, rocky plateaus, and salt flats. **Reasons for Aridness** - Like the Sahara, the Arabian Desert is located in a subtropical high-pressure belt. This region is dominated by descending dry air, resulting in high temperatures and minimal rainfall, fostering its arid conditions. - Also, the desert’s environment is compounded by the effects of regional winds that can lead to the formation of dry dust storms, further reducing moisture in the area.

Gobi Desert

The Gobi Desert is a unique cold desert located in northern China and southern Mongolia. Unlike its hotter counterparts, the Gobi experiences harsh temperatures that can vary from scalding hot summers to freezing cold winters. The primary factor behind the Gobi's dryness is its inland position, far from any large body of water that could provide moisture. Without maritime influences, any potential rain-bearing systems often dissipate before reaching the desert. Additionally, the rain shadow effect created by nearby mountain ranges further deprives the area of precipitation, blocking moist air currents from entering.

subtropical high-pressure zones

Subtropical high-pressure zones are significant in shaping the arid landscapes of many of Earth's deserts. These zones form approximately between 20° and 30° north and south of the equator and are marked by warm, dry air descending to the surface. **Characteristics of High-Pressure Zones** - These stable air zones prevent the rise of moist air, blocking cloud formation and precipitation.
- The lack of clouds leads to intense solar radiation and high day temperatures, followed by sharp temperature drops at night because of the absence of insulating cloud cover.
The dominance of these high-pressure zones across specific latitudes contributes significantly to the desertification of these regions, maintaining their aridity over long periods.

Intertropical Convergence Zone (ITCZ)

The Intertropical Convergence Zone, or ITCZ, is a crucial component of Earth’s climatic system, heavily influencing weather patterns around the equator. It is characterized by a belt of low pressure that encircles the globe, where the trade winds from the Northern and Southern hemispheres meet. **Key Features of the ITCZ** - The converging winds force warm, moist air to rise, leading to its cooling and condensation into clouds and precipitation.
- This process results in a continuous band of clouds and heavy rainfall, forming a distinctive feature visible from space around the equatorial zone.
The movement and intensity of the ITCZ vary seasonally, significantly impacting the climate and weather patterns of tropical regions, often leading to sporadic rainy and dry seasons as it shifts.