PLANET S is a hypothetical replica of Earth. It has plate tectonics, oceans, and an atmosphere very similar to Earth’s. You will map the climatic zones on this planet, identifying cold and warm ocean currents, prevailing winds, potential locations of rain forests and deserts, places where the climate and topographic setting would be suitable for […]

GLOBAL ENERGY, HYDROLOGIC SYSTEMS, AND BIOLOGIC SYSTEMS are interdependent, linked by processes, like photosynthesis, evapotranspiration, and albedo, through a system of complicated feedbacks. How does the climate stay at conditions favorable for life, despite the fact that it is always changing? Alternatively, can the biosphere help sustain a favorable environment through such self-regulating processes? This […]

COMPUTER MODELS are used to investigate issues related to climate, like global warming. The simplest climate models compute energy (temperature), water, or momentum for a small area over a limited time. The most complicated models use numerical methods and principles of physics to compute atmospheric conditions at many vertical levels across the entire Earth, for […]

CLIMATE CHANGE HAS MANY IMPACTS, ranging from obvious ones like an increase in global temperatures, to less obvious ones, such as a possible increase in malaria and other diseases. Some of these consequences are highly probable, whereas others are very speculative. On these pages, we briefly introduce some of the most likely results of climate […]

CLIMATE CHANGE IS ALWAYS OCCURRING, including global warming since the mid-1800s. There are many natural causes of climate change, including changes in Earth’s orbit around the Sun and changes in sunspot activity. Many scientists propose that human activities, including the burning of fossil fuels and the clearing of forests, also contribute to climate change by […]

OVER THE LAST 150 YEARS, people have measured atmospheric temperatures. This record, albeit short in geological terms, shows an overall increase in temperatures — global warming. There is currently much scientific and political discussion of this topic. What is the evidence that Earth’s climate is changing? What Is Climate Change? Earth’s climate has been changing […]

THE CLIMATE OF A PLACE is a combination of the regional atmospheric conditions, such as those expressed by the Koppen climate classification, and local effects caused by topography, local wind directions, pollution, and other factors. These result in local variations, commonly called the local climate or the microclimate. The local climate is greatly influenced by […]

AIR POLLUTION consists of gases, liquids, and solids introduced into the atmosphere by human activities and deemed to be detrimental to humans and other creatures, plants, or other aspects of ecosystems. Most air pollution consists of noxious gases and liquids, car exhaust, and smoke and soot from industrial activities and fires. What Is Air Pollution […]

POLAR AND ADJACENT SUBPOLAR CLIMATES occur at very high latitudes in both the Northern and Southern Hemispheres. Climates of polar regions, assigned to Group E in the Koppen system, are extremely cold and are subdivided into Ice Cap (EF) and Tundra climate (ET). Farther from the pole, the Tundra climate gives way to another Group D […]

NON-ARID, MID-LATITUDE CLIMATES tend to experience a relatively even distribution of precipitation year-round. Some are dominated by maritime air masses that moderate temperature swings and result in relatively mild winters and summers; they are within Group C in the Koppen designation. Other mid-latitude climates impart more severe winters because they are dominated by continental air […]

TEMPERATE MID-LATITUDE CLIMATES, designated as Group C of the Koppen system, experience moderate temperatures and precipitation and so are sites of particularly intense human activity. Some temperate climates are relatively warm, because they occur mostly in subtropical latitudes. These include Humid Subtropical, Mediterranean, and Temperate Monsoon climates. What Is the Spatial Distribution of the Various […]

ARID CLIMATES OCCUPY a greater portion of Earth’s land surface than any other climate category. They comprise Group B in the Koppen classification and are subdivided into desert climates and steppe climates, with the distinction being that deserts are more arid than steppes. Deserts and Steppes are further subclassified into hot or cold categories — […]

A-TYPE CLIMATES in the Koppen climatic classification system are “tropical,” having consistently warm temperatures all year. Precipitation in these zones is primarily caused by the convergence of the trade winds along the Intertropical Convergence Zone (ITCZ), which shifts with the season to locations north and south of the equator. There are three types of A […]

EACH TYPE OF CLIMATE, as defined by the Koppen climate classification, has specific characteristics that distinguish it from any other climate type. Once a climate is assigned to one of the five main groups (A–E), it is then categorized by factors such as whether most precipitation falls in the summer, winter, throughout the year, or […]

THE KOPPEN CLIMATE CLASSIFICATION was defined for land areas and generally is depicted as a map covering a large area and portraying the regional or global distributions of different climate types. The map on these two pages covers the entire planet and is an Extended Koppen Classification, because we have extended the land-defined Koppen classification […]

CLASSIFICATION IS THE PROCESS of grouping similar items together and separating dissimilar items. Items that are similar in some ways can be different in others, and items that are in different groups can have certain similarities. Classifications allow us to examine general patterns, with the caveat that interpretations derived from classified groups are best done […]

CLIMATE IS THE LONG-TERM PATTERN of weather at a place, including not just the average condition but also the variability and extremes of weather. It largely reflects an area's geographic setting, especially latitude, elevation, and position relative to the ocean. Climate is also influenced by atmospheric pressure and moisture, prevailing and seasonal wind directions, and […]

THE SOUTHERN ISTHMUS OF CENTRAL AMERICA is geographically and climatically one of the most interesting places in the world. It is a narrow strip of land that connects Central America and South America and that separates very different waters of the Pacific and Atlantic Oceans. The climate of the region reflects intricately changing wind patterns […]

The Sahara remains the preeminent example of a midlatitude desert formed as a result of the way in which heating at the equator drives the atmospheric circulation of the whole planet. Moist, heated air rises high into the atmosphere at the equator, which draws the steady flow of the trade winds in the midlatitudes. The […]

The fractured mix of coastline and mountain across northernmost Colombia and Venezuela is laced with small-scale weather regimes that violate the normal rules of climate. As the childhood home of novelist Gabriel Garcia Marquez, this land was fertile ground for the blend of magic and realism that permeates his writing. Garcia Marquez grew up in […]

It's the biggest environment challenge our world has ever faced, but that doesn't mean global warming is insoluble. Here are a few ways you can make a difference. Calculate your carbon. Through a variety of online tools, you can determine how much carbon is produced by your daily activities – the perfect starting point for […]

If you can't get next week's weather right, how can you claim to predict anything a year in advance? It's the difference between weather and climate that makes long-lead forecasts possible. Actual storms can't be predicted a year out, but the longer-term features that affect climate across a season can sometimes be foretold with surprising […]

Nobody really experiences climate per se. You can experience weather any time just by stepping outside, but climate is the average of sun, rain, snow, wind and other elements playing out over the long haul. This makes it an abstraction, built from the fragments of weather that caress or assault us. Even so, climate is […]

Science-fiction master Robert Heinlein once pointed out, “Climate is what you expect; weather is what you get'That, in a nutshell, is the difference between the two. Weather refers to the day-to-day vagaries of the atmosphere, the conditions that change from hour to hour and from day to day. Climate deals with the average of weather […]

Oil, coal and gas may be set to run out in the next century or so, but should we be using them in the first place? People have always known that fossil fuels present problems. Oil causes environmental damage when it leaks from pipelines or ships. Burning it produces a wide range of pollutants. The […]

What should we do with our growing awareness that we are altering the Earth's climate? Some think that innovation, especially in energy technology, will sort it all out, given some political will and an awareness that there is profit in it. This is more or less this author's line, although I also think that time […]

How do animals and people manage to live in the Arctic? Ask Karl Georg Christian Bergmann (1814-65). This German medic and anatomist worked out that as conditions get colder, animals get bigger. In the US, a much-studied example of Bergmann's Rule is the Song Sparrow. Members of this widespread species that live by the sea […]

In addition to the annual cycle of the seasons, there are longer-term cycles at play which affect the amount of energy the Earth receives from the Sun, causing significant variations in the Earths climate. First, there have now been almost 400 years of routine observations of the Sun which show that sunspots appear on its surface […]

A HUMAN PERSPECTIVE During the Vietnam War, American troops were sent to fight in unfamiliar Southeast Asia. Among the hardships they endured was the tropical climate. Few had ever lived in a place that had a monsoon season with constant rain. One soldier wrote to his wife, “We live in mud and rain. I'm so […]

A HUMAN PERSPECTIVE Kublai Khan was the ruler of the Mongol Empire (which included China) in the 13th century. In 1281, the Great Khan sent a huge fleet against Japan. A typhoon—a tropical storm that occurs in the western Pacific—swept across the Sea of Japan and sank the Mongol ships or dashed them against the […]

A HUMAN PERSPECTIVE Every April and May, much of South Asia bakes in the heat. People endure temperatures that regularly top 100°F. Dust fills the air, and streams dry up. People walk for miles looking for water. Then—when it seems that no one can survive another day—the clouds roll in. The skies open up, and […]

A HUMAN PERSPECTIVE In the spring of 1999, three Canadian explorers retraced the steps of Sir Wilfred Thesiger's 1946 epic journey across the Rub al-Khali on the Arabian Peninsula. It is one of the most extreme deserts in the world. Like Sir Wilfred, they crossed using camels, not four-wheel drive vehicles. But unlike Sir Wilfred, […]

A HUMAN PERSPECTIVE In 1352, 48-year-old Ibn Battuta, a great traveler from Morocco, set out for the empire of Mali in West Africa. His most challenging obstacle was the Sahara, a desert nearly the same size as the continental United States. Battuta and his caravan set out in February. They traveled only in early morning […]

A HUMAN PERSPECTIVE Large areas of Russia and the Republics are extremely cold during much of the year. For example, the Siberian town of Oymyakon has reportedly had temperatures as low as –95°F. At such temperatures, the cold can crack steel and cause tires to explode. When you exhale, your breath freezes into crystals that […]

A HUMAN PERSPECTIVE Because of Greece's mild climate, the ancient Greeks spent much time outdoors. Greek men liked to talk with their friends in the marketplace. They also enjoyed sports. Large crowds gathered for athletic contests that were held during religious festivals. The most important of these was a footrace held every four years in […]

A HUMAN PERSPECTIVE In the 17th century, missionaries and Indians in the area of present-day Paraguay were at times attacked by jaguars, the great cats of Latin America. In 1637, packs of jaguars roamed the countryside, attacking humans. The Indians built barricades for protection from the savage cats. But the jaguars remained a source of […]

A HUMAN PERSPECTIVE A little gold and bitter cold—that is what thousands of prospectors found in Alaska and the Yukon Territory during the Klondike gold rushes of the 1890s. Most of these fortune hunters were unprepared for the harsh climate and inhospitable land of the far north. Winters were long and cold, the ground frozen. […]

Types of Climates World climates are generally divided into five large regions: tropical, dry, mid-latitude, high latitude, and highland. The regions are divided into smaller subregions that are described below. TROPICAL WET This subregion has little variation in temperature over the year—it is always hot, with an average temperature of 80°F. The days begin sunny […]

A HUMAN PERSPECTIVE Nineteenth-century fishermen along the Peruvian coast called the event El Nino—the Spanish name for the infant Jesus—because the event occurred near Christmastime. Every two to seven years, the waters off the Peruvian coast became warmer than usual, resulting in poor fishing. Eventually, 20th-century scientists studying worldwide climate changes confirmed the truth of […]

CLIMATE GRADIENTS AND BIOME TYPES As we have seen, biomes and formation classes change along with climate. Figure 9.34 shows three continental transects that illustrate this principle. The upper transect stretches from the Equator to the Tropic of Cancer in Africa. Across this region, climate ranges through all four low-latitude climates: wet equatorial, monsoon and trade-wind coastal, wet-dry tropical , […]

By and large, the high-latitude climates are climates of the northern hemisphere, occupying the northern subarctic and arctic latitude zones. But they also extend southward into the midlatitude zone as far south as about the 47th parallel in eastern North America and eastern Asia. One of these, the ice sheet climate, is present in both hemispheres in the polar zones. The […]

The midlatitude climates almost fully occupy the land areas of the midlatitude zone and a large proportion of the subtropical latitude zone. They also extend into the subarctic latitude zone, along the western fringe of Europe, reaching to the 60th parallel. Unlike the lowlatitude climates, which are about equally distributed between northern and southern hemispheres, nearly all of the midlatitude climate area […]

The low-latitude climates lie for the most part between the Tropics of Cancer and Capricorn, occupying all of the equatorial zone (10° N to 10° S), most of the tropical zone (10–15° N and S), and part of the subtropical zone. The low-latitude climate regions include the equatorial trough of the intertropical convergence zone (ITCZ), the belt of tropical easterlies (northeast and […]

Mean monthly values of air temperature and precipitation can describe the climate of a weather station and its nearby region quite accurately. To study climates from a global viewpoint, climatologists classify these values into distinct climate types. This classification requires developing a set of rules to use in examining monthly temperature and precipitation values. By applying the rules, a climatologist can use […]

Climate is the average weather of a region. The primary driving force for weather is the flow of solar energy received by the Earth and atmosphere. Because that energy flow varies on daily cycles with the planet's rotation and on annual cycles with its revolution in orbit, temperature and precipitation also vary on daily and annual cycles. However, climate includes […]

The diverse climates of Africa range from scorching deserts to icy glaciers, from steamy rainforests to grassy plains. Climate is a long-term weather pattern, the sum of features such as temperature, rainfall, and wind. The amount of heat from the sun plays a major role in determining climate. The equator receives more solar heat than any other part of the […]

Introduction Communities which cope with climatic hazards by im plicitly assuming a continuance of the status quo learn harsh lessons. Despite this, quite limited adaptation to known risks is often apparent in contemporary society. In the past, the catastrophe of harvest failure led to sometimes quite sophisticated coping responses and the shunning of areas of known high risk based on […]

MICROCLIMATES ARE climates of small areas, such as gardens, cities, lakes, valleys, and forests. A microclimate is an expression of the temperature, humidity, and wind within a few feet or meters of the ground. Such expressions exist because surfaces vary in their ability to absorb, store, or reflect the sun's energy, making some areas warmer […]

CLIMATE IS an average or aggregate of daily weather conditions over a period of years. Latitude, distance from oceans, atmospheric and oceanic circulation pattern, elevation, and local geographical features control the climate of a place. The controls of climate result in a plethora of interrelated elements of climate, ranging from temperature, pressure, wind, humidity, clouds, […]

THE TERM climate refers to the long-term averages of insolation (solar radiation absorbed by Earth), temperature, precipitation, cloud cover, air masses, atmospheric pressure, winds, and cloud coverage. Of these, temperature and precipitation are the most important factors in establishing climate type. A place may have rain on one day, clear conditions for a week, and […]