Slow mass movement of soil downslope that is initiated by freeze-thaw action. Occurs where the stresses on the slope material are too small to create a rapid failure.
The net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal (perpendicular) to the ground surface and settles in a nearly vertical direction.
The net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal to the ground surface and settles in a nearly vertical direction
The net downslope displacement that occurs when a soil, during a freeze-thaw cycle, expands normal to the ground surface and settles in a nearly vertical direction.
An observational day on which frost occurs; one of a family of climatic indicators (e.g., thunderstorm day, rain day). The definition is somewhat arbitrary, depending upon the accepted criteria for a
frost observation. Thus, it may be 1) a day on which the minimum air temperature in the thermometer shelter falls below 0C (32F); 2) a day on which a deposit of white frost is observed on the ground; 3) in British usage, a day on which the minimum temperature at the level of the ground or on the tops of low, close-growing vegetation falls to -0.9C (30.4F) or below (also called a "day with ground frost"); and perhaps others. The present trend is to drop such terms in favor of something less ambiguous, such as "day with minimum temperature below 0C (32F)."
Crystals of ice that form when water vapor becomes a solid (bypassing the liquid phase) and deposits itself on the sea ice surface; frost flowers roughen the surface and dramatically affect its electr
omagnetic signal.
Growth of ice crystals by condensation from the atmosphere at points on the surface of young ice. After formation sea water may be drawn through the ice into the flowers.
Number of frost free days is calculated based on the last occurrence of frost in spring and the first occurrence of frost in autumn. This is an especially important parameter for agriculture, because
the variability in the number of frost free days is crucial for many agricultural activities such as planting and harvesting, but the impact of a strong frost can become an economic problem that affects the prices.
The period, usually expressed in days, between the last observed occurrence of frost in the spring and the first observed occurrence of frost in the autumn.
The risk of damage by frost. It may be expressed as the probability or frequency of killing frost on different dates during the growing season, or as the distribution of dates of the last killing fros
t of spring or the first of autumn. A strict application of the concept would take into account the actual species or group of plants that might potentially be killed, as different plants sustain frost damage at different temperatures. Wind-chill factors should also be considered.
The upward or outward movement of the ground surface caused by the formation of Ice in the soil. Frost Action in fine-grained soils increases the volume of the soil not only by freezing of in situ por
e water (9% expansion) but also by drawing water to the Freezing Front where Ice lenses form. Soils that have undergone substantial heaving may consist of alternate layers of Ice-saturated soil and relatively clear Ice lenses. The lenses are formed normal to the direction of heat flow and when freezing penetrates from the ground surface (which may be horizontal, sloping or vertical), they form parallel to that surface. When unrestrained, the amount of surface heave may be almost as much as the total thickness of the Ice lenses. Frost Heave can occur seasonally or continuously if freezing of the ground proceeds without interruption over a period of years. Differential, or non-uniform, frost heaving is one of the main aspects of the Frost Action process and reflects the heterogeneous nature of most soils, or variations in heat removal rate and groundwater supply over short distances. Depending on the degree of restraint, large Freezing Pressures (up to 1 MPa) can be developed as the ground freezes.
A local bowl-shaped region or depression in the surface in which, in suitable conditions, cold air accumulates during the night as the result of cold air drainage called katabatic wind. Such regions a
re subject to a greater incidence of frost, and to more severe frosts, than are the surrounding areas of nonconcave shape. (Also known as frost pocket in agricultural/gardening)