Weather and climate

The Intertropical Convergence Zone (ITCZ) is a belt near the equator where trade winds meet, usually shifting a few degrees north and south with the seasons. It circles the globe over the tropics rather than staying in one fixed place.

The Roaring Forties are found in the Southern Hemisphere, roughly between 40° and 50° south latitude. They are famous for strong westerly winds over the Southern Ocean.

Trade winds blow in the tropics on both sides of the equator, between about 30° latitude and the equator. They generally flow from east to west.

The eyewall is the ring of intense storms surrounding the calm eye at the center of a hurricane. It is located just outside the eye and contains the strongest winds and heaviest rain.

The eye of a tornado is at the center of the rotating column of air, though tornadoes do not always have a clear visible “eye” like hurricanes do. The calmest air is usually closest to the center, surrounded by the violent vortex.

Jet streams are found high in the atmosphere near the tropopause, typically around 8 to 16 kilometers above Earth’s surface. They are narrow bands of very fast winds that circle the planet.

The polar vortex is centered over the Arctic and Antarctic regions high in the atmosphere, especially in winter. It is a large circulation of cold air around each pole.

Monsoon regions are found mainly around South Asia, Southeast Asia, East Asia, West Africa, and northern Australia. They occur where seasonal wind reversals bring wet and dry periods.

El Niño forms in the equatorial Pacific Ocean, especially the central and eastern tropical Pacific. It begins when sea-surface temperatures there become unusually warm.

La Niña forms in the equatorial Pacific Ocean, especially the central and eastern tropical Pacific. It is the cooler phase of the ENSO cycle.

The ocean conveyor belt is a global circulation system connecting all major oceans, from the North Atlantic to the deep Pacific and Southern Ocean. It moves through both surface and deep currents.

The ozone hole is located over Antarctica, mainly in the stratosphere above the South Pole region. It appears each spring in the Southern Hemisphere.

The greenhouse effect operates throughout Earth’s atmosphere, but it is most important in the lower atmosphere and over places with lots of water vapor and cloud cover. It is a global process, not a single location.

Permafrost is found in high-latitude Arctic regions and in high mountains around the world. It is ground that stays frozen for at least two consecutive years.

Coral bleaching hot spots are found in warm tropical seas, especially where ocean temperatures rise above normal for weeks at a time. Famous examples include parts of the Great Barrier Reef, the Caribbean, and the central Pacific.

The Saharan Air Layer forms over North Africa, above the Sahara Desert, and often moves westward across the Atlantic Ocean. It is a hot, dry, dusty air mass.

Haboobs are most commonly found in arid and semi-arid regions such as the Sahara, the Middle East, and parts of the southwestern United States. They are intense dust storms caused by thunderstorm outflow winds.

Lake-effect snow belts are found downwind of large lakes, especially the Great Lakes in North America. They form where cold air passes over relatively warmer water.

Chinook winds are found on the lee side of the Rocky Mountains, especially in parts of western Canada and the northern United States. They are warm, dry downslope winds.

Föhn winds are found on the lee side of mountain ranges, especially the Alps in central Europe. They are warm, dry downslope winds.

The Santa Ana wind region is in Southern California, especially inland areas flowing toward the Los Angeles basin and the coast. These are hot, dry winds that blow from the desert toward the sea.

A sea breeze front forms along coastlines where cool marine air moves inland and meets warmer land air. It is common near oceans, seas, and large lakes.

The Atacama’s rain shadow is on the western side of the Andes in northern Chile and southern Peru. Moist air loses much of its rain on the eastern slopes before reaching the coast.

Köppen climate zones are mapped across the entire Earth. The classification is used globally to compare climate regions by temperature and rainfall.

The urban heat island effect is strongest in dense cities with lots of pavement, buildings, and little vegetation. It is a local climate effect found in urban areas worldwide.

One of Earth’s major lightning hotspots is Lake Maracaibo in Venezuela, especially near the Catatumbo River delta. It is famous for frequent lightning storms.

One of the world’s highest long-running weather stations is on Mount Everest in the Himalayas, at the South Col and near the summit region. These stations operate at extreme altitude above 8,000 meters.

The World Meteorological Organization is headquartered in Geneva, Switzerland. It is a specialized agency of the United Nations.

The Hadley Cell is centered in the tropics, rising near the equator and descending around 30 degrees latitude in both hemispheres.

El Niño is usually observed in the central and eastern tropical Pacific Ocean, especially along the coast of South America. It is linked to unusually warm sea-surface temperatures there.

The Pacific Decadal Oscillation is centered in the North Pacific Ocean. It is a long-term pattern of ocean temperature and circulation changes.

The North Atlantic Oscillation is measured over the North Atlantic between the subtropical high near the Azores and the Icelandic low. It is not a single place, but a pressure pattern across the ocean basin.

The Antarctic ozone hole is most often observed over Antarctica, especially above the South Pole region in spring. It forms in the lower stratosphere.

The world’s highest average rainfall is recorded at Mawsynram in Meghalaya, India. The village is famous for extremely heavy monsoon rain.

The temperate rainforest of the Pacific Northwest stretches along the coast from northern California through Oregon, Washington, and into British Columbia and southeast Alaska. It is one of the wettest forest regions outside the tropics.

The Siberian High forms over interior Asia, centered on Siberia and Mongolia in winter. It is one of the strongest and coldest high-pressure systems on Earth.

The West African monsoon is centered over West Africa, especially the Gulf of Guinea and the Sahel region. It brings seasonal rains northward from the tropical Atlantic.

The Indian summer monsoon is strongest over the Indian subcontinent, especially the western coast, northeastern India, and the Western Ghats. It is a major seasonal rain system.

The East Asian monsoon is centered over eastern China, Korea, Japan, and nearby seas. It brings hot, humid summers and cold, dry winters to the region.

Mediterranean climate zones are found around the Mediterranean Basin and in a few other regions such as coastal California, central Chile, the Cape region of South Africa, and southwest Australia. They have dry summers and wet winters.

Jet streams are found high in the troposphere near the boundaries between major air masses. The best-known ones circle the mid-latitudes of both hemispheres.

The stratosphere lies above the troposphere and below the mesosphere, starting at roughly 10 to 15 kilometers above Earth’s surface. It extends upward to about 50 kilometers.

The troposphere is the lowest layer of Earth’s atmosphere, starting at the surface and reaching about 8 to 18 kilometers high. Most weather happens there.

The Sahel climate is located in a broad belt just south of the Sahara Desert, stretching across Africa from the Atlantic Ocean to the Red Sea. It is a semi-arid transition zone.

Permafrost is most widespread in the Arctic, especially across Siberia, Alaska, northern Canada, and Greenland. It is ground that remains frozen for at least two consecutive years.

The snow line is found on mountains and at high latitudes where snow persists year-round. Its altitude changes with climate, latitude, and season.

The rain shadow effect is typically found on the leeward side of mountain ranges. Air drops much of its moisture on the windward side, leaving the other side drier.

The monsoon trough is usually located over South and Southeast Asia during the monsoon season, but it can shift across the Indian subcontinent and into nearby waters. It is a zone of low pressure and storms.

The Bering Sea climate is strongly influenced in the North Pacific and subarctic region between Alaska and Russia. Sea ice and storms shape its weather.

The Atacama Desert’s climate is shaped along the Pacific coast of northern Chile and southern Peru. The cold Humboldt Current helps keep it extremely dry.

The Namib Desert is influenced by coastal fog along the Atlantic coast of southwestern Africa, mainly in Namibia. The cold Benguela Current helps produce the fog.

One of the world’s longest continuous climate records comes from ice cores in Antarctica, especially at sites like Dome C and Vostok. These cores preserve ancient air and snowfall layers.