3. Snow#

Snow characteristics#

  • Colors

  • Crystal structure

Snow formation#

  • A general rule: snow will not form if the ground temperature is at least 5°C.

  • Temperature vs moisture (Antarctica’s Dry Valley!)

  • Most snowflakes are less than 1.3 cm.

  • Snow seasonality

Vertical profile of ground snow#

  • Daytime temperature inversion

Snow water equivalent#

  • Definition: the thickness of water that would result from melting a given layer of snow.

  • 25 cm of fresh snow ~= 0.25-10 cm of water.

  • New snow in the U.S. contains a water-to-snow ratio between 4-10%.

Snow and weather#

  • Snow forecasting remains challenging.

  • Follow storm tracks in boreal winter.

  • Blizzard and bomb cyclone

  • Thunder snow (summer)

  • Polar vortex

Snow and vegetation#

  • Wind direction

  • Canopy snow

  • Tree type

  • Clearings

Snowpack energy budget#

  • Snow albedo

  • Latent heat of snow

  • Turbulent transfer

Snow and rain temperature#

../_images/snow_rain_1.webp

Lake effect snow#

../_images/snow_lake_effect1.jpg

Snow and climate change#

  • Snow trend and variability

  • Snow as a forcing to affect atmospheric circulation?

../_images/snow_trend.png

Fig. 4 March snow water equivalent and its trend (per decade). Source: Pullianinen et al. (2020)#

Snow-atmosphere coupling#

../_images/snow_atm_coupling.png

Fig. 5 Wavy red arrows indicate interaction between surface snow cover and regional enhancement of upward-propagating Rossby wave activity, with the stratospheric polar vortex represented by ‘L’ with anticlockwise flow. Resultant enhanced Rossby wave activity and troughing is indicated by the orange line. This figure us from Henderson et al. (2018).#

Literature review#

Sources#