Erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.
In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field whose value at a point is the "direction and rate of fastest increase". If the gradient of a function is non-zero at a point , the direction of the gradient is the direction in which the function increases most quickly from , and the magnitude of the gradient is the rate of increase in that direction, the greatest absolute directional derivative. Further, a point where the gradient is the zero vector is known as a stationary point. The gradient thus plays a fundamental role in optimization theory, where it is used to maximize a function by gradient ascent. In coordinate-free terms, the gradient of a function may be defined by:
In mathematics, the slope or gradient of a line is a number that describes both the direction and the steepness of the line. Slope is often denoted by the letter m; there is no clear answer to the question why the letter m is used for slope, but its earliest use in English appears in O'Brien (1844) who wrote the equation of a straight line as "y = mx + b" and it can also be found in Todhunter (1888) who wrote it as "y = mx + c".
Alpine skiing, or downhill skiing, is the pastime of sliding down snow-covered slopes on skis with fixed-heel bindings, unlike other types of skiing, which use skis with free-heel bindings. Whether for recreation or for sport, it is typically practiced at ski resorts, which provide such services as ski lifts, artificial snow making, snow grooming, restaurants, and ski patrol.
A trail, also known as a path or track, is an unpaved lane or a small paved road not intended for usage by motorized vehicles, usually passing through a natural area. In the United Kingdom and the Republic of Ireland, a path or footpath is the preferred term for a pedestrian or hiking trail. The term is also applied in North America to accompanying routes along rivers, and sometimes to highways. In the US, the term was historically used for a route into or through wild territory used by explorers and migrants. In the United States, "trace" is a synonym for trail, as in Natchez Trace.
An avalanche is a rapid flow of snow down a slope, such as a hill or mountain.
A bicycle frame is the main component of a bicycle, onto which wheels and other components are fitted. The modern and most common frame design for an upright bicycle is based on the safety bicycle, and consists of two triangles: a main triangle and a paired rear triangle. This is known as the diamond frame. Frames are required to be strong, stiff and light, which they do by combining different materials and shapes.
In mathematics, gradient descent is a first-order iterative optimization algorithm for finding a local minimum of a differentiable function. The idea is to take repeated steps in the opposite direction of the gradient of the function at the current point, because this is the direction of steepest descent. Conversely, stepping in the direction of the gradient will lead to a local maximum of that function; the procedure is then known as gradient ascent. It is particularly useful in machine learning for minimizing the cost or loss function. Gradient descent should not be confused with local search algorithms, although both are iterative methods for optimization.
The grade of a physical feature, landform or constructed line refers to the tangent of the angle of that surface to the horizontal. It is a special case of the slope, where zero indicates horizontality. A larger number indicates higher or steeper degree of "tilt". Often slope is calculated as a ratio of "rise" to "run", or as a fraction in which run is the horizontal distance and rise is the vertical distance.
The pedal is the part of a bicycle that the rider pushes with their foot to propel the vehicle. It provides the connection between the cyclist's foot or shoe and the crank allowing the leg to turn the bottom bracket spindle and propel the bicycle's wheels. A pedal usually consists of a spindle that threads into the end of the crank, and a body on which the foot rest is attached, that is free to rotate on bearings with respect to the spindle.
A contour line of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional graph of the function parallel to the -plane. More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value.
In meteorology, prevailing wind in a region of the Earth's surface is a surface wind that blows predominantly from a particular direction. The dominant winds are the trends in direction of wind with the highest speed over a particular point on the Earth's surface at any given time. A region's prevailing and dominant winds are the result of global patterns of movement in the Earth's atmosphere. In general, winds are predominantly easterly at low latitudes globally. In the mid-latitudes, westerly winds are dominant, and their strength is largely determined by the polar cyclone. In areas where winds tend to be light, the sea breeze/land breeze cycle is the most important cause of the prevailing wind; in areas which have variable terrain, mountain and valley breezes dominate the wind pattern. Highly elevated surfaces can induce a thermal low, which then augments the environmental wind flow.
Cyclo-cross is a form of bicycle racing. Races typically take place in the autumn and winter, and consist of many laps of a short course featuring pavement, wooded trails, grass, steep hills and obstacles requiring the rider to quickly dismount, carry the bike while navigating the obstruction and remount. Races for senior categories are generally between 40 minutes and an hour long, with the distance varying depending on the ground conditions. The sport is strongest in the traditional road cycling countries such as Belgium, France and the Netherlands.
Wenlock Edge is a limestone escarpment near Much Wenlock, Shropshire, England and a site of special scientific interest because of its geology. It is over 19 mi (31 km) long, running southwest to northeast between Craven Arms and Much Wenlock, and is roughly 1,083 feet above sea level. The deciduous woodland which runs along it covers much of the steep slopes of the escarpment and in parts it is very well preserved.
In physical geography and physical geology, aspect is the compass direction or azimuth that a terrain surface faces.
A piste is a marked ski run or path down a mountain for snow skiing, snowboarding, or other mountain sports.
Bicycle performance is measurable performance such as energy efficiency that affect how effective a bicycle is. Bicycles are extraordinarily efficient machines; in terms of the amount of energy a person must expend to travel a given distance, cycling is calculated to be the most efficient self-powered means of transportation.
In topography, the line of greatest slope is a curve following the steepest slope. In mountain biking and skiing, the line of greatest slope is sometimes called the fall line.
Mountain bike trials, also known as observed trials, is a discipline of mountain biking in which the rider attempts to pass through an obstacle course without setting foot to ground. Derived from motorcycle trials, it originated in Catalonia, Spain as trialsín and is said to have been invented by Pere Pi, the father of Ot Pi, a world champion motorcycle trials rider. Pi's father had wanted his son to learn motorcycle trials by practicing on an ordinary bicycle.
This glossary of skiing and snowboarding terms is a list of definitions of terms and jargon used in skiing, snowboarding, and related winter sports.
