# Notes from Labs Flashcards

The equation for density

mass/volume

comment on the density profile of a snowpack discussing what may be causing the variation with depth

The density is the lightest at the top. It gets denser as you go down for awhile, and then progressively gets less dense as you go deeper. The reason it gets denser at first is due to gravitational setting where an increase in pressure more efficiently packs the particles. It then gets less dense because of the deposition of the water between crystals which rises and condenses at colder portions of the snow pack forming depth hoar.

How to find the energy required to melt a snowpack

Pick an assumed volume, find it’s dimensions and then solve for the Warming, ripening and output phases. Then add them all up.

What are the coefficients in this equation for the ripening phase?

Qm2 = θ(ret)h(s)ρ(w)λ(f)

Things in parenthesis are subscripts.

θret = -0.0745(ρs/ρw) + 0.000267(ρs/ρw)2 and is the amount of water a snowpack can retain against gravity

hs = height of the snowpack

ρw = the density of water

λf = the latent heat of fusion for water (334 J/g)

Theissen Method

The theissen method gives a weighted average to each individual gauge

Disscus the strengths and weaknesses of the arithmetic mean to find the average annual precipitation

A strength of the arithmetic mean is that it is fast and easy to calculate. It would be the lease afccurate because the gauges could have been placed very close to eachother and then you would be taking those readings into too much account, or large areas with no precipitation could be ignored.

Discuss the strenghts and weakness of the isohyetal method to find the average annual percipitation

Good because it takes all areas into account. One downfall of this is that you may not have enough rain gauges to accurately draw the isoheytal lines, which could mess up your percent of total area. Also you are assuming that in between each line there is the same amount of rainfall for that area.

(This is the method where you draw lines similar to a topographic map across areas, find the area, and then take a weighted average)

Discuss the strengths and weaknesses of the theissen method for determining average annual percipitation

It is good because is uses the real rain gauge amounts for each area. It’s weakness is that if 2 rain gauges are very apart there may not be the average between thoses gauges halfway between them, it may be closer to one than the other.

How to find the overland flow after the flood peak passes

D equals A^0.2

Where d equals days and A equals area

In the equation to determine the velocity of flow what do the coefficients mean?

V equals 1/n*R^(2/3)*S^(1/2)

S is slope

R is area/wetted perimeter

n is a coefficient

V is measured in m/s

Equation for relative humidity

absolute humidity/capacity * 100

Volume of a cyllinder

V equals pi*R^2*h