Needle ice is a needle-shaped column of ice formed by groundwater. Needle ice forms when the temperature of the soil is above 0 °C (32 °F) and the surface temperature of the air is below 0 °C (32 °F).

If you ever had the soil crunch underfoot on a cold morning, then it is likely you were walking on needle ice. Such needle ice would not be as impressive as above, but still, it is needle ice. Once I started looking for ice, I noticed that one area of bare …

2024年12月20日 · Needle ice occurs when the ground temperature is above freezing and the air temperature is below freezing. it most typically forms in loose soil high in silt and organic matter such as you might find along stream beds, in agricultural fields around loose rocks, and other places in which soil is deep and can absorb and retain lots of water.

2023年2月22日 · Needle ice is a form of ice segregation. Soil moisture is usually fairly evenly distributed throughout the soil, but when ice segregation occurs, that soil moisture migrates to certain points in the soil and freezes in clumps, “segregated” from the rest of the soil.

Needle ice forms when the temperature of the soil is above 0 °C and the surface temperature of the air is below 0 °C. Liquid water underground rises to the surface by capillary action, and then freezes and contributes to a growing needle-like ice column.

2020年1月22日 · The key to needle ice formation is that the air has to be much cooler than the wet soil. So needle ice tends to form at night, when the air is coolest and the temperature gradient the greatest. It also tends to form on trails where foot traffic breaks down leaf litter and roots, exposing the wet soils to the cold air.

Needle ice forms when the ground is saturated, then freezes rapidly. The ice crystals grow upward, starting a few centimeters (inches) underground. If the air stays cold enough, needle ice can grow 40 centimeters (16 inches) long.

2016年2月29日 · Frost forms when water vapor is deposited onto a growing ice crystal; the water molecules move directly from the gas phase to the solid phase without ever becoming a liquid. Needle ice, on the other hand, forms from liquid water when a process called ice segregation occurs in the soil.

2024年4月5日 · What is Needle Ice? A quick lesson in science. Don’t be afraid. When the air temperature at ground level is below 32° F, but the soil temperature is just above 32°, the conditions are set. This most often happens on clear mountain nights when the air temperatures drop precipitously after a warm sunny day.

2025年1月1日 · The Japanese word for needle ice, shimobashira, translates as “columns of frost.” Needle ice can be defined as “the accumulation of ice crystal growths in the direction of heat loss at, or directly beneath, the ground surface.”