Dry season

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Dry season in Laos. Long shadow of a dead tree with its branches on the dry fields of Don Det, a sunny day with blue sky and white clouds, late afternoon. Long shadow of a dead tree with its branches on the dry fields of Laos - landscape.jpg
Dry season in Laos. Long shadow of a dead tree with its branches on the dry fields of Don Det, a sunny day with blue sky and white clouds, late afternoon.

The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year.

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Rain belt

The tropical rain belt lies in the southern hemisphere roughly from October to March; during that time the northern tropics have a dry season with sparser precipitation, and days are typically sunny throughout. From April to September, the rain belt lies in the northern hemisphere, and the southern tropics have their dry season. Under the Köppen climate classification, for tropical climates, a dry season month is defined as a month when average precipitation is below 60 millimetres (2.4 in). [1]

The rain belt reaches roughly as far north as the Tropic of Cancer and as far south as the Tropic of Capricorn. Near these latitudes, there is one wet season and one dry season annually. At the equator there are two wet and two dry seasons, as the rain belt passes over twice a year, once moving north and once moving south. Between the tropics and the equator, locations may experience a short wet and a long wet season; and a short dry and a long dry season. Local geography may substantially modify these climate patterns, however.

Drought

During the dry season, humidity is very low, causing some watering holes and rivers to dry up. This lack of water (and hence of food) may force many grazing animals to migrate to more fertile spots. Examples of such animals are zebras, elephants, giraffe, rhinoceros, antelope and wildebeest, water buffalo, cape buffalo, gaur, tapir, emu, ostrich, rhea, kangaroos. Because of the lack of water in the plants, bushfires (wildfires) are common. [2]

Diseases

Data shows that in Africa the start of the dry season coincides with a rise in the cases of measles—which researchers believe might be attributed to the higher concentration of people in the dry season, as agricultural operations are all but impossible without irrigation. During this time, some farmers move into cities, creating hubs of higher population density, and allowing the disease to spread more easily. [3]

Research

New data shows that in the seasonal parts of the South American Amazon rainforest, foliage growth and coverage varies between the dry and wet seasons—with about 25% more leaves and faster growth in the dry season. Researchers believe that the Amazon itself has an effect in bringing[ clarification needed ] the onset of the wet season: by growing more foliage, it evaporates more water. [4] However, this growth appears only in the undisturbed parts of the Amazon basin, where researchers believe roots can reach deeper and gather more rainwater. [5] It has also been shown that ozone levels are much higher in the dry than in the wet season in the Amazon basin. [6]

Related Research Articles

Geography of Nigeria

Nigeria is a country in West Africa. Nigeria shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in the north. It also shares a border with the self-declared, but internationally unrecognized state of Ambazonia in the southeast. Its coast lies on the Gulf of Guinea in the south and it borders Lake Chad to the northeast. In the southeast, it also shares a border with the breakaway state of Ambazonia. Noted geographical features in Nigeria include the Adamawa highlands, Mambilla Plateau, Jos Plateau, Obudu Plateau, the Niger River, River Benue and Niger Delta.

Tropics Region of Earth surrounding the Equator

The tropics are the region of Earth surrounding the Equator. They are delimited in latitude by the Tropic of Cancer in the Northern Hemisphere at 23°26′11.6″ (or 23.43654°) N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′11.6″ (or 23.43654°) S; these latitudes correspond to the axial tilt of the Earth. The tropics are also referred to as the tropical zone and the torrid zone. The tropics include all zones on Earth where the Sun contacts a point directly overhead at least once during the solar year. Thus the maximum latitudes of the tropics have the same value positive and negative. Likewise, they approximate, due to the earth not being a perfect sphere, the "angle" of the Earth's axial tilt. The "angle" itself is not perfectly fixed due chiefly to the influence of the moon, but the limits of tropics are a geographic convention, being an averaged form, and the variance is very small.

Tropic of Capricorn Line of southernmost latitude at which the sun can be directly overhead

The Tropic of Capricorn is the circle of latitude that contains the subsolar point at the December solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reaches 90 degrees below the horizon at solar midnight on the June Solstice. Its northern equivalent is the Tropic of Cancer.

Tropical and subtropical moist broadleaf forests Habitat type defined by the World Wide Fund for Nature

Tropical and subtropical moist forest (TSMF), also known as tropical moist forest, is a tropical and subtropical forest habitat type defined by the World Wide Fund for Nature. The habitat type is sometimes known as jungle.

Queensland tropical rain forests

The Queensland tropical rain forests ecoregion covers a portion of the coast of Queensland in northeastern Australia and belonging to the Australasian realm. The forest contains the world's best living record of the major stages in the evolutionary history of the world’s land plants, including most of the world's relict species of plants from the ancient supercontinent of Gondwana. The history of the evolution of marsupials and songbirds is also well represented.

Precipitation Product of the condensation of atmospheric water vapor that falls under gravity

In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzling, rain, sleet, snow, ice pellets, graupel and hail. Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation but colloids, because the water vapor does not condense sufficiently to precipitate. Two processes, possibly acting together, can lead to air becoming saturated: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers.

Subtropics Geographic and climate zone

The subtropical zones or subtropics are geographic and climate zones located to the north and south of the tropical zone. Geographically part of the north and south temperate zones, they cover the latitudes between 23°26′11.6″ and approximately 35° in the northern hemisphere and in the southern hemisphere.

Tropical climate Climate in the tropical region

Tropical climate is one of the five major climate groups in the Köppen climate classification. Tropical climates are characterized by monthly average temperatures of 18 ℃ (64.4 ℉) or higher year-round and feature hot temperatures. Annual precipitation is often abundant in tropical climates, and shows a seasonal rhythm to varying degrees. There are normally only two seasons in tropical climates, a wet season and a dry season. The annual temperature range in tropical climates is normally very small. Sunlight is intense.

Köppen climate classification Climate classification system

The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, notably in 1918 and 1936. Later, the climatologist Rudolf Geiger (1894-1981) introduced some changes to the classification system, which is thus sometimes called the Köppen–Geiger climate classification system.

Tropical rainforest Specific ecosystem

Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforest. True rainforests are typically found between 10 degrees north and south of the equator ; they are a sub-set of the tropical forest biome that occurs roughly within the 28-degree latitudes. Within the World Wildlife Fund's biome classification, tropical rainforests are a type of tropical moist broadleaf forest that also includes the more extensive seasonal tropical forests.

Wet season

The wet season is the time of year when most of a region's average annual rainfall occurs. Generally, the season lasts at least a month. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the tropics and subtropics.

Rainfall and the tropical climate dominate the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year, roughly following the solar equator. The tropical rain belt is an area of active rain that is positioned mostly around the tropics.

A tropical marine climate is a tropical climate that is primarily influenced by the ocean. It is usually experienced by islands and coastal areas 10° to 20° north and south of the equator. There are two main seasons in a tropical marine climate: the wet season and the dry season. The annual rainfall is 1000 to over 1500 mm. The temperature ranges from 20 °C to 35 °

Climate of Brazil

The climate in Brazil varies considerably from mostly tropical north to temperate zones south of the Tropic of Capricorn.

Tropical savanna climate Climate subtype

Tropical savanna climate or tropical wet and dry climate is a type of climate that corresponds to the Köppen climate classification categories Aw and As. The driest month has less than 60 mm (2.4 in) of precipitation and also less than of precipitation.

Tropical rainforest climate Type of tropical climate in which there is no dry season

A tropical rainforest climate or equatorial climate is a tropical climate usually found within 10 to 15 degrees latitude of the equator, and has at least 60 millimetres (2.4 in) of rainfall every month of the year. Regions with this climate are typically designated Af by the Köppen climate classification. A tropical rainforest climate is typically hot, very humid, and wet.

Rain Precipitation in the form of water droplets

Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides suitable conditions for many types of ecosystems, as well as water for hydroelectric power plants and crop irrigation.

Tropical monsoon climate Climate subtype in the Köppen climate classification system

An area of tropical monsoon climate is a type of climate that corresponds to the Köppen climate classification category "Am". Tropical monsoon climates have monthly mean temperatures above 18 °C (64 °F) in every month of the year and a dry season. Tropical monsoon climates is the intermediate climate between the wet Af and the drier Aw.

Seasonal tropical forest

Seasonal tropical forest, also known as moist deciduous, semi-evergreen seasonal, tropical mixed or monsoon forests, typically contain a range of tree species: only some of which drop some or all of their leaves during the dry season. This tropical forest is classified under the Walter system as (ii) tropical climate with high overall rainfall concentrated in the summer wet season and dry season: representing a range of habitats influenced by monsoon (Am) or tropical wet savannah (Aw) climates. Drier forests in the Aw climate zone are typically deciduous and placed in the Tropical dry forest biome: with further transitional zones (ecotones) of savannah woodland then tropical and subtropical grasslands, savannas, and shrublands.

Eastern Java–Bali rain forests

The Eastern Java-Bali rain forests ecoregion covers the lowland areas of the eastern half of the island of Java, and the island of Bali, in Indonesia. This ecoregion is distinct from the Eastern Java-Bali montane rain forests, which exists at higher altitudes where mountain forest habitat dominates. Very little of the natural lowland rainforest remains in its pre-human settlement state.

References

  1. "Updated world Köppen-Geiger climate classification map" (PDF).
  2. "Wet & Dry Seasons". Archived from the original on 2012-03-21. Retrieved 2008-04-21.
  3. "Dry Season Brings On Measles In Sub-Saharan Africa". ScienceDaily. February 7, 2008.
  4. "Amazon rainforest does have rainy and dry seasons". mongabay.com. March 12, 2007. Archived from the original on June 4, 2008.
  5. "Amazon rainforest greens up in the dry season".
  6. V. W. J. H. Kirchhoff, I. M. O. Da Silva, E. V. Browell (1990). "Ozone measurements in Amazonia: Dry season versus wet season". Journal of Geophysical Research. 95 (D10): 16913. Bibcode:1990JGR....9516913K. doi:10.1029/jd095id10p16913.CS1 maint: multiple names: authors list (link)