iPhoneOgraphy – 23 Dec 2016 (Day 358/366)
Deciduous means “falling off at maturity” ” or “tending to fall off”, and it is typically used in order to refer to trees or shrubs that lose their leaves seasonally (most commonly during autumn) and to the shedding of other plant structures such as petals after flowering or fruit when ripe. In a more general sense, deciduous means “the dropping of a part that is no longer needed” or “falling away after its purpose is finished”. In plants it is the result of natural processes. “Deciduous” has a similar meaning when referring to animal parts, such as deciduous antlers in deer or deciduous teeth, also known as baby teeth, in some mammals (including humans).
In botany and horticulture, deciduous plants, including trees, shrubs and herbaceous perennials, are those that lose all of their leaves for part of the year. This process is called abscission. In some cases leaf loss coincides with winter – namely in temperate or polar climates. In other parts of the world, including tropical, subtropical, and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall.
The converse of deciduous is coniferous, where foliage is shed on a different schedule from deciduous trees, therefore appearing to remain green year round. Plants that are intermediate may be called semi-deciduous; they lose old foliage as new growth begins. Other plants are semi-evergreen and lose their leaves before the next growing season, retaining some during winter or dry periods. Some trees, including a few species of oak, have desiccated leaves that remain on the tree through winter; these dry persistent leaves are called marcescent leaves and are dropped in the spring as new growth begins.
Many deciduous plants flower during the period when they are leafless, as this increases the effectiveness of pollination. The absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, result in water stress on the plant. Nevertheless, there is much less branch and trunk breakage from glaze ice storms when leafless, and plants can reduce water loss due to the reduction in availability of liquid water during cold winter days.
Leaf drop or abscission involves complex physiological signals and changes within plants. The process of photosynthesis steadily degrades the supply of chlorophylls in foliage; plants normally replenish chlorophylls during the summer months. When autumn arrives and the days are shorter or when plants are drought-stressed, deciduous trees decrease chlorophyll pigment production, allowing other pigments present in the leaf to become apparent, resulting in non-green colored foliage. The brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing. These other pigments include carotenoids that are yellow, brown, and orange. Anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, when sugars are trapped in the leaves after the process of abscission begins. Parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees simply fall off without turning the bright colors produced from the accumulation of anthocyanin pigments.
Plants with deciduous foliage have advantages and disadvantages compared to plants with evergreen foliage. Since deciduous plants lose their leaves to conserve water or to better survive winter weather conditions, they must regrow new foliage during the next suitable growing season; this uses resources which evergreens do not need to expend. Evergreens suffer greater water loss during the winter and they also can experience greater predation pressure, especially when small. Losing leaves in winter may reduce damage from insects; repairing leaves and keeping them functional may be more costly than just losing and regrowing them. Removing leaves also reduces cavitation which can damage xylem vessels in plants. This then allows deciduous plants to have xylem vessels with larger diameters and therefore a greater rate of transpiration (and hence CO2 uptake as this occurs when stomata are open) during the summer growth period.
The deciduous characteristic has developed repeatedly among woody plants. Trees include maple, many oaks and nothofagus, elm, aspen,and birch, among others, as well as a number of coniferous genera, such as larch and Metasequoia. Deciduous shrubs include honeysuckle, viburnum, and many others. Most temperate woody vines are also deciduous, including grapes, poison ivy, Virginia creeper, wisteria, etc. The characteristic is useful in plant identification; for instance in parts of Southern California and the American Southeast, deciduous and evergreen oak species may grow side by side.
Periods of leaf fall often coincide with seasons: winter in the case of cool-climate plants or the dry-season in the case of tropical plants, however there are no deciduous species among tree-like monocotyledonous plants, e.g. Palms, yuccas, and dracaenas.
iPhoneOgraphy – 17 Dec 2016 (Day 352/366)
Ski mountaineering is a skiing discipline that involves climbing mountains either on skis or carrying them, depending on the steepness of the ascent, and then descending on skis. There are two major categories of equipment used, free-heel Telemark skis and skis based on Alpine skis, where the heel is free for ascents, but is fixed during descent. The discipline may be practiced recreationally or as a competitive sport.
Competitive ski mountaineering is typically a timed racing event that follows an established trail through challenging winter alpine terrain while passing through a series of checkpoints. Racers climb and descend under their own power using backcountry skiing equipment and techniques. More generally, ski mountaineering is an activity that variously combines ski touring, Telemark, backcountry skiing, and mountaineering. It is planned by the Union Internationale des Associations d’Alpinisme (UIAA), to make ski mountaineering by itself part of the 2018 Olympic Games.
Military patrol was an official event at the 1924 Winter Olympics, followed by demonstration events at the 1928 Winter Olympics, in 1936 and in 1948. Military patrol is considered to be a predecessors of the biathlon.
From 1992 to 2009, the Comité International du Ski-Alpinisme de Compétition (CISAC), founded by France, Italy, Slovakia, Andorra and Switzerland, sanctioned the European Championship. Then the CISAC merged with the International Council for Ski Mountaineering Competitions in 1999, which in 2008 became the International Ski Mountaineering Federation (ISMF).
Outside Europe, international championships started with the 2007 South American Ski Mountaineering Championship and the 2007 Asian Championship of Ski Mountaineering. The 2012 North American Ski Mountaineering Championship was the first edition of a North American Championship of Ski Mountaineering, sanctioned by the United States Ski Mountaineering Association.
A ski resort is a resort developed for skiing, snowboarding, and other winter sports. In Europe, most ski resorts are towns or villages in or adjacent to a ski area – a mountainous area with pistes, ski trails and a ski lift system. In North America, it is more common for ski areas to exist well away from towns, so ski resorts usually are destination resorts, often purpose-built and self-contained, where skiing is the main activity.
Ski areas have marked paths for skiing known as runs, trails or pistes. Ski areas typically have one or more chairlifts for moving skiers rapidly to the top of hills, and to interconnect the various trails. Rope tows can also be used on short slopes (usually beginner hills or bunny slopes). Larger ski areas may use gondolas or aerial trams for transportation across longer distances within the ski area.
Ski areas usually have at least a basic first aid facility, and some kind of ski patrol service to ensure that injured skiers are rescued. The ski patrol is usually responsible for rule enforcement, marking hazards, closing individual runs (if a sufficient level of hazard exists), and removing (dismissing) dangerous participants from the area.
Some ski resorts offer lodging options on the slopes themselves, with ski-in and ski-out access allowing guests to ski right up to the door. Ski resorts often have other activities, such as snowmobiling, sledding, horse-drawn sleds, dog-sledding, ice-skating, indoor or outdoor swimming, and hot tubbing, game rooms, and local forms of entertainment, such as clubs, cinema, theaters and cabarets. Après-ski (French: after skiing) is a term for entertainment, nightlife or social events that occur specifically at ski resorts. These add to the enjoyment of resort-goers and provide something to do besides skiing and snowboarding. The culture originated in the Alps, where it is most popular and where skiers often stop at bars on their last run of the day while still wearing all their ski gear. People that browse ski resort & hotel websites will commonly seek mention of the quality of après-ski in the area, and such information is often found. It is therefore seen as an important factor for skiers to consider before booking a holiday. The concept is similar to the nineteenth hole in golf.
Though the word ‘ski’ is a derivation of the Old Norse ‘skíð’ via Norwegian, the choice of French is likely attributed to the early popularity of such activities in the French Alps, with which it was then linked.
iPhoneOgraphy – 09 Dec 2016 (Day 344/366)
Snow pertains to frozen crystalline water throughout its life cycle, starting when it precipitates from clouds and accumulates on surfaces, then metamorphoses in place, and ultimately melts, slides or sublimates away. Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime. As snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering, sublimation and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form. Otherwise, snow typically melts, seasonally, and causes runoff into streams and rivers and recharging groundwater.
Major snow-prone areas include the Arctic and Antarctica, the upper half of the Northern Hemisphere, and alpine regions.
Scientists study snow at a wide variety of scales that include the physics of chemical bonds and clouds; the distribution, accumulation, metamorphosis, and ablation of snowpacks; and the contribution of snowmelt to river hydraulics and ground hydrology. In doing so, they employ a variety of instruments to observe and measure the phenomena studied. Their findings contribute to knowledge applied by engineers, who adapt vehicles and structures to snow, by agronomists, who address the availability of snowmelt to agriculture, and those, who design equipment for sporting activities on snow. Scientists develop and others employ snow classification systems that describe its physical properties at scales ranging from the individual crystal to the aggregated snowpack. A sub-specialty is avalanches, which are of concern to engineers and outdoors sports people, alike.
Snow affects such human activities as transportation: creating the need for keeping roadways, wings, and windows clear; agriculture: providing water to crops and safeguarding livestock, and such sports as skiing, snowboarding, and snow machine travel. Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold.