Week 12 Flashcards
Ice formation
Snow
Neve
Firn
Ice
Why does resolution of isotope ratios decrease with depth of ice?
Compaction
What does the cyclical trend help us eliminate?
Aperiodic trends e.g. volcanism
What is the concept of Rayleigh distillation?
When water vapour cools to certain T it condenses; equilibrium fractionation occurs between vapour and condensing phases
Equilibrium fractionation of heavy isotopes i.e. 18O and 2H
Snow very effective
The Rayleigh distillation “effects”
Latitude (due to T)
Continental
Altitude
T
Rainout
(Amount)
(Source isotope ratio)
Value of SMOW
1/499
+ve 18O% means
More 18O than SMOW
What is the effect of T on the equilibrium fractionation factor?
Lower T = higher
Epsilon
Rain enriched with respect to water vapour, increases when rain —> snow
Reasons for EUGRIP and NGRIP differences
Rainout
Different trajectories
T-18O relationships vary…
Site to site
Original air mass
Trajectory
Who/when measured
CET facts
From 1659
UK Midlands b/w Bristol/Lancashire/London
