Bulgaria Ski discussion board
More sun starting to appear on the forecast
Author:
posts : 13 (Beginner)Date : 01-14-10 13:52More sun starting to appear on the forecast
Weather forecast is starting to show signs of sun again
re: More sun starting to appear on the forecast
yes but prediction of temperatures -7/-8 at bottom resort level...and remember snow reflects UV light so it wont melt
re: More sun starting to appear on the forecast
Hi DaveI don't work for the met office but are you sure sun does'nt melt snow ?
re: More sun starting to appear on the forecast
Love it Nelly
re: More sun starting to appear on the forecast
Simples!!
Snowmelt Energy Balance –How and Why does Snow Melt
. Snowmelt Calculations
The goal is to calculate the amount and rate of water loss given climate information.
To melt snow we have to add energy to the snowpack first to warm the pack then to melt the pack. Snowmelt calculations are based on conservation of energy
Ein – Eout = change in stored energy
DtS = DQ
The melt period begins at the end of the accumulation period and occurs in 3 phases
1. Warming
2. ...
Snowmelt Energy Balance –How and Why does Snow Melt
. Snowmelt Calculations
The goal is to calculate the amount and rate of water loss given climate information.
To melt snow we have to add energy to the snowpack first to warm the pack then to melt the pack. Snowmelt calculations are based on conservation of energy
Ein – Eout = change in stored energy
DtS = DQ
The melt period begins at the end of the accumulation period and occurs in 3 phases
1. Warming
2. ...
Simples!!
Snowmelt Energy Balance –How and Why does Snow Melt
. Snowmelt Calculations
The goal is to calculate the amount and rate of water loss given climate information.
To melt snow we have to add energy to the snowpack first to warm the pack then to melt the pack. Snowmelt calculations are based on conservation of energy
Ein – Eout = change in stored energy
DtS = DQ
The melt period begins at the end of the accumulation period and occurs in 3 phases
1. Warming
2. Ripening
4. Output
5.1 Warming Phase
The temperature of the snowpack increases until the whole pack is 0C.
The pack must overcome the “cold content” which is given by
Qcc = -ciDwhm(Ts-Tm)
ci is the heat capacity of ice = 2102 J/kg-K
Ts = snow temperature
Tm = 0C
Qcc can be considered an energy deficit. As energy flows into the snowpack, it first has to fill the bucket represented by Qcc before any melt can occur.
5.2 Ripening phase
Now we are melting snow.
Water stays in the pack.
Snow has a water holding capacity
hwret = θreths
In the ripening phase we melt ice until hwret is satisified.
Qm2 = rwlfhwret
lf = 79.7 cal/g = 0.334 MJ/kg
5.3 Output Phase
Qm3 = rwlf (hm – hwret)
The total energy required to melt a snowpack
Qt = Qm1+Qm2+Qm3
K
Snowmelt Energy Balance –How and Why does Snow Melt
. Snowmelt Calculations
The goal is to calculate the amount and rate of water loss given climate information.
To melt snow we have to add energy to the snowpack first to warm the pack then to melt the pack. Snowmelt calculations are based on conservation of energy
Ein – Eout = change in stored energy
DtS = DQ
The melt period begins at the end of the accumulation period and occurs in 3 phases
1. Warming
2. Ripening
4. Output
5.1 Warming Phase
The temperature of the snowpack increases until the whole pack is 0C.
The pack must overcome the “cold content” which is given by
Qcc = -ciDwhm(Ts-Tm)
ci is the heat capacity of ice = 2102 J/kg-K
Ts = snow temperature
Tm = 0C
Qcc can be considered an energy deficit. As energy flows into the snowpack, it first has to fill the bucket represented by Qcc before any melt can occur.
5.2 Ripening phase
Now we are melting snow.
Water stays in the pack.
Snow has a water holding capacity
hwret = θreths
In the ripening phase we melt ice until hwret is satisified.
Qm2 = rwlfhwret
lf = 79.7 cal/g = 0.334 MJ/kg
5.3 Output Phase
Qm3 = rwlf (hm – hwret)
The total energy required to melt a snowpack
Qt = Qm1+Qm2+Qm3
K
re: More sun starting to appear on the forecast
Everyone knows that K tell us something we don't knowre: More sun starting to appear on the forecast
The long winter evenings fly by in our house!
re: More sun starting to appear on the forecast
Qt = Qm1+Qm2+Qm3 isnt happening in borovets....re: More sun starting to appear on the forecast
There you go Dave I am boring you are succinctre: More sun starting to appear on the forecast
UV light contains more energy than visible light, snow is a very good reflector of UV ... which i was on about not temperature, temperatures are in the minuses at the moment.
Quote
The measured UV albedo values of most natural surfaces are smaller than 10% (Feister et al., 1995; McKenzie
et al., 1996), but for fresh pure snow UV albedos near unity have been reported (Grenfell et al., 1994; Wuttke etal., 2006).
Albedos of typical materials in visible light range from up to 90% for ...
Quote
The measured UV albedo values of most natural surfaces are smaller than 10% (Feister et al., 1995; McKenzie
et al., 1996), but for fresh pure snow UV albedos near unity have been reported (Grenfell et al., 1994; Wuttke etal., 2006).
Albedos of typical materials in visible light range from up to 90% for ...
UV light contains more energy than visible light, snow is a very good reflector of UV ... which i was on about not temperature, temperatures are in the minuses at the moment.
Quote
The measured UV albedo values of most natural surfaces are smaller than 10% (Feister et al., 1995; McKenzie
et al., 1996), but for fresh pure snow UV albedos near unity have been reported (Grenfell et al., 1994; Wuttke etal., 2006).
Albedos of typical materials in visible light range from up to 90% for fresh snow, to about 4% for charcoal, one of the darkest substances.
Quote
The measured UV albedo values of most natural surfaces are smaller than 10% (Feister et al., 1995; McKenzie
et al., 1996), but for fresh pure snow UV albedos near unity have been reported (Grenfell et al., 1994; Wuttke etal., 2006).
Albedos of typical materials in visible light range from up to 90% for fresh snow, to about 4% for charcoal, one of the darkest substances.
