ROCHESTER, N.Y. – This beginning to be the time of year when many people begin looking forward to the gradual melting of the snowpack. When conditions are favorable, the snow can melt away completely and eventually signal the transition toward spring.
This process is especially important for those living in rural areas. For homes that rely on well water, melting snow plays a critical role in replenishing local creeks and streams, which in turn helps recharge the groundwater system.
The basic process is straightforward. As snow melts, it changes from the solid phase—ice crystals—into the liquid phase, or water, and the snowpack gradually diminishes as runoff moves into the surrounding environment.
However, there is another process that can reduce the snowpack, and it occurs for very different reasons. It is called sublimation, and it can take place even when temperatures remain below freezing. Sublimation happens when snow transitions directly from the solid phase into water vapor, skipping the liquid phase altogether. In this case, the snow does not melt, but simply disappears into the atmosphere.
When sublimation occurs, none of that moisture contributes to groundwater recharge. Instead, the water vapor is lost to the atmosphere, reducing the overall snowpack without providing any benefit to soil moisture.
Sublimation is most effective when sunshine and wind are present, as both help accelerate the process. Fog can also contribute under certain conditions. Some estimates suggest that mountainous areas and exposed hilltops can lose between 10 and 30 percent of their snowpack due to sublimation alone.
The post First Alert Weather In-Depth: When snow vanishes without melting appeared first on WHEC.com.
