how many climate zones are there in the world
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A hardiness zone (a subcategory of Vertical Zonation) is a geographically defined area in which a specific category of plant life is capable of growing, as defined by climatic conditions, including its ability to withstand the minimum temperatures of the zone (see the scale on the right or the table below). For example, a plant that is described as "hardy to zone 10" means that the plant can withstand a minimum temperature of -1Â°C. A more resilient plant that is "hardy to zone 9" can tolerate a minimum temperature of -7Â°C. First developed for the United States by the Department of Agriculture (USDA), the use of the zones has been adopted by other nations.
USDA Hardiness Zones
Benefits and drawbacks
The hardiness zones are informative: the extremes of winter cold are a major determinant of whether a plant species can be cultivated outdoors at a particular location; however, the USDA hardiness zones have a number of drawbacks if used without supplementary information.
The zones do not incorporate summer heat levels into the zone determination; thus sites which may have the same mean winter minima, but markedly different summer temperatures, will be accorded the same hardiness zone. An extreme example of this phenomenon is seen when comparing the Shetland Islands and southern Alabama, which are both on the boundary of zones 8 and 9 and share the same winter minima, but little else in their climates. In summer, the humid subtropical climate of Alabama is about 20 degrees Celsius hotter than the Maritime Subarctic climate of Shetland, and there are few similar plants that can be grown at both locations. Due to its maritime climate, the UK is in AHS Heat Zone 2 (having 1 to 8 days hotter than 30 degrees Celsius) according to the AHS (American Horticultural Society), whereas Alabama is in Zones 7 to 9 (61 to 150 days hotter than 30 degrees Celsius). Users need to combine the hardiness zone with the heat zone to gain greater understanding of what can be grown in a particular location.
Another issue is that the hardiness zones do not take into account the reliability of the snow cover. Snow acts as an insulator against extreme cold, protecting the root system of hibernating plants. If the snow cover is reliable, the actual temperature to which the roots are exposed will not be as low as the hardiness zone number would indicate. As an example, Quebec City in Canada is located in zone 4, but can rely on an important snow cover every year, making it possible to cultivate plants normally rated for zones 5 or 6. But, in Montreal, located to the southwest in zone 5, it is sometimes difficult to cultivate plants adapted to the zone because of the unreliable snow cover.
Other factors that affect plant survival, though not considered in hardiness zones, are soil moisture, humidity, the number of days of frost, and the risk of a rare catastrophic cold snap. Some risk evaluation â€“ the probability of getting a particularly severe low temperature â€“ often would be more useful than just the average conditions.
Lastly, many plants may survive in a locality but will not flower if the day length is insufficient or if they require vernalization (a particular duration of low temperature). With annuals, the time of planting can often be adjusted to allow growth beyond their normal geographical range.
An alternative means of describing plant hardiness is to use "indicator plants" (the USDA also publishes a list of these to go with the hardiness zone map). In this method, common plants with known limits to their range are used.
Gardening books are available that provide more information on climate zones. For example, Sunset Books (associated with Sunset Magazine) publishes a series that break up climate zones more finely than the USDA zones. They identify 45 distinct zones in the US, incorporating ranges of temperatures in all seasons, precipitation, wind patterns, elevation, and length and structure of the growing season.
Britain and Ireland Hardiness Zones
Owing to the moderating effect of the Gulf Stream on the Irish and Britishtemperatemaritime climate, Britain, and Ireland even more so, have milder winters than their northerly position suggests. This means that the hardiness zones relevant to Britain and Ireland are quite high, from 7 to 10, as shown below.
- 7. In Scotland the Grampians, Highlands and locally in the Southern Uplands, in England the Pennines and in Wales the highest part of Snowdonia.
- 8. Most of England, Wales and Scotland, and parts of central Ireland.
- 9. Most of western and southern England and Wales, western Scotland, also a very narrow coastal fringe on the east coast of Scotland and northeast England (within 5 km of the North Sea), London, and most of Ireland.
- 10. Very low lying coastal areas of the southwest of Ireland and the Isles of Scilly.
Central Europe Hardiness Zones
Central Europe's climate is a good example of a transition from an oceanic climate to a continental climate, which can be noticed immediately when looking at the hardiness zones, which tend to decrease mainly eastwards instead of northwards. Also, the plateaux and low mountain ranges in this region have a significant impact on how cold it might get during winter. Generally speaking, the hardiness zones are high considering the latitude of the region, although not as high as in the Shetland Islands where zone 9 extends to over 60Â°N. In Central Europe, the relevant zones decrease from zone 8 on the Belgian and
The intertidal zone (also known as the foreshore and seashore and sometimes referred to as the littoral zone) is the area that is exposed to the air at low tide and underwater at high tide (for example, the area between tide marks). This area can include many different types of habitats,with many types of animals like starfish, sea urchants, and some species of coral. the well known area also includes steep rocky cliffs, sandy beaches, or wetlands (e.g., vast mudflats). The area can be a narrow strip, as in Pacific islands that have only a narrow tidal range, or can include many meters of shoreline where shallow beach slope interacts with high tidal excursion.
Organisms in the intertidal zone are adapted to an environment of harsh extremes. Water is available regularly with the tides but varies from fresh with rain to highly saline and dry salt with drying between tidal inundations. The action of waves can dislodge residents in the littoral zone. With the intertidal zone's high exposure to the sun the temperature range can be anything from very hot with full sun to near freezing in colder climates. Some microclimates in the littoral zone are ameliorated by local features and larger plants such as mangroves. Adaption in the littoral zone is for making use of nutrients supplied in high volume on a regular basis from the sea which is actively moved to the zone by tides. Edges of habitats, in this case land and sea, are themselves often significant ecologies, and the littoral zone is a prime example.
A typical rocky shore can be divided into a spray zone or splash zone (also known as the supratidal zone), which is above the spring high-tide line and is covered by water only during storms, and an intertidal zone, which lies between the high and low tidal extremes. Along most shores, the intertidal zone can be clearly separated into the following subzones: high tide zone, middle tide zone, and low tide zone.
Marine biologists and others divide the intertidal region into three zones (low, middle, and high), based on the overall average exposure of the zone. The low intertidal zone, which borders on the shallow subtidal zone, is only exposed to air at the lowest of low tides and is primarily marine in character. The mid intertidal zone is regularly exposed and submerged by average tides. The high intertidal zone is only covered by the highest of the high tides, and spends much of its time as terrestrial habitat. The high intertidal zone borders on the swash zone (the region above the highest still-tide level, but which receives wave splash). On shores exposed to heavy wave action, the intertidal zone will be influenced by waves, as the spray from breaking waves will extend the intertidal zone.
Depending on the substratum and topography of the shore, additional features may be noticed. On rocky shores, tide pools form at lowis trapped in hollows. Under certain conditions, such as those at Morecambe Bay, quicksand may form.
Low tide zone (lower littoral)
This subregion is mostly submerged - it is only exposed at the point of low tide and for a longer period of time during extremely low tides. This area is teeming with life; the most notable difference with this subregion to the other three is that there is much more marine vegetation, especially seaweeds. There is also a great biodiversity. Organisms in this zone generally are not well adapted to periods of dryness and temperature extremes. Some of the organisms in this area are abalone, anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, nudibranchs, sculpin, sea cucumber, sea lettuce, sea palms, sea stars, sea urchins, shrimp, snails, sponges, surf grass, tube worms, and whelks. Creatures in this area can grow to larger sizes because there is more available energy in the localised ecosystem and because marine vegetation can grow to much greater sizes than in the other three intertidal subregions due to the better water coverage: the water is shallow enough to allow plenty of light to reach the vegetation to allow substantial From Yahoo Answers
Answers:United States to the south and with the U.S. state of Alaska to the northwest, stretching from the Atlantic Ocean in the east to the Pacific Ocean in the west; to the north lies the Arctic Ocean. By total area (including its waters), Canada is the second largest country in the world after Russia and largest on the continent. By land area it ranks fourth. Since 1925, Canada has claimed the portion of the Arctic between 60 W and 141 W longitude, but this claim is not universally recognized. The northernmost settlement in Canada and in the world is Canadian Forces Station (CFS) Alert on the northern tip of Ellesmere Island latitude 82.5 N just 817 kilometres (450 nautical miles) from the North Pole. Canada has the longest coastline in the world: 243,000 kilometres. The population density, 3.5 inhabitants per square kilometre (9.1/sq mi), is among the lowest in the world. The most densely populated part of the country is the Quebec City-Windsor Corridor along the Great Lakes and Saint Lawrence River in the southeast. To the north of this region is the broad Canadian Shield, an area of rock scoured clean by the last ice age, thinly soiled, rich in minerals, and dotted with lakes and rivers. Canada by far has more lakes than any other country and has a large amount of the world's freshwater. A Maritime scene at Peggys Cove, Nova Scotia, which has long been sustained by the Atlantic fisheryIn eastern Canada, most people live in large urban centres on the flat Saint Lawrence Lowlands. The Saint Lawrence River widens into the world's largest estuary before flowing into the Gulf of Saint Lawrence. The gulf is bounded by Newfoundland to the north and the Maritimes to the south. The Maritimes protrude eastward along the Appalachian Mountain range from northern New England and the Gasp Peninsula of Quebec. New Brunswick and Nova Scotia are divided by the Bay of Fundy, which experiences the world's largest tidal variations. Ontario and Hudson Bay dominate central Canada. West of Ontario, the broad, flat Canadian Prairies spread toward the Rocky Mountains, which separate them from British Columbia. In northwestern Canada, the Mackenzie River flows from the Great Slave Lake to the Arctic Ocean. A tributary of a tributary of the Mackenzie is the South Nahanni River, which is home to Virginia Falls, a waterfall about twice as high as Niagara Falls. Mount Robson, Canadian Rockies in British Columbia.Northern Canadian vegetation tapers from coniferous forests to tundra and finally to Arctic barrens in the far north. The northern Canadian mainland is ringed with a vast archipelago containing some of the world's largest islands. Average winter and summer high temperatures across Canada vary depending on the location. Winters can be harsh in many regions of the country, particularly in the interior and Prairie provinces which experience a continental climate, where daily average temperatures are near 15 C (5 F) but can drop below 40 C ( 40 F) with severe wind chills. In non-coastal regions, snow can cover the ground almost six months of the year (more in the north). Coastal British Columbia is an exception and enjoys a temperate climate with a mild and rainy winter. On the east and west coast, average high temperatures are generally in the low 20s C (70s F), while between the coasts the average summer high temperature ranges from 25 to 30 C (75 to 85 F) with occasional extreme heat in some interior locations exceeding 40 C (104 F). For a more complete description of climate across Canada see Environment Canada's Website. Canada is also geologically active, having many earthquakes and potentially active volcanoes, notably Mount Meager, Mount Garibaldi, Mount Cayley and the Mount Edziza volcanic complex. The volcanic eruption of Tseax Cone in 1775 caused a catastrophic disaster, killing 2,000 Nisga'a people and the destruction of their village in the Nass River valley of northern British Columbia; the eruption produced a 22.5 km (14 mi) lava flow and according to legend of the Nisga'a people, it blocked the flow of the Nass River.[76
Answers:In general you can easily grow plants from one hardiness zone below and above the one you live in. The trick is understanding the microclimate around your home. The south side of your house is generally warmer. Overhanging evergreen trees can protect plants from frost damage. Over the years I have come to understand there are many climate factors besides cold hardiness that affect growing success. Most plants are winter hardy in several zones. However, some plants winter hardy in zone 5 may not like the heat of your area in summer. There are now heat zone maps for the U.S. See link below. You can also search "zone 6 plants" and so on for info. Rainfall can also affect success. Saying a plant has drought hardiness where rainfall is 40" per year may not apply to a dry year in an area with a normal rainfall of 30" per year. Link to annual rainfall rates below. Tropical plants will die down when the temperature hits freezing. The plants you listed are not likely to produce fruit due to the limited growing season. Zone 9 is the coldest area of commercial production for oranges, which can survive freezing, but will not reliably produce fruit in zone 8. There are some tropical plants that normally go dormant during summer drought that will react to freezing weather as their normal dormancy, and return in spring, like elephant ears. This is limited by how deeply the ground freezes though. For most of the U.S. tropicals must be placed in a heated greenhouse over winter. As to arctic and subarctic plants the first link below provides some good information for a starter.
Answers:Warm temperate climates are found in the following regions and countries: The Mediterranean Basin; South Africa; Australia; New Zealand; Eastern Asia; western coastal regions of North America (mainly California); and western coastal regions of South America (mainly Chile). Plants in these climate zones have special adaptations that allow them to survive seasonally harsh conditions, especially drought, and in some cases, fire. Here are some features to look out for: small, fine leaves, which help decrease transpiration and conserve water; hairy leaves, which accomplish the same job and capture water droplets from fog; silver leaves, which reflect solar radiation; and shrubby stature, due to regular recovery from burning. There are other adaptations that you won't see, notably the underground features of geophytic plants, which die back in the drought season and draw on the food reserves in their corms, rhizomes, tubers, or bulbs.
Answers:Try this map: http://upload.wikimedia.org/wikipedia/commons/c/c2/ClimateMapWorld.png The major climatic zone is subarctic.