Lecture 6 Energy Exchange & Winter

Ng below freezing and not freeze something needs to

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Unformatted text preview: A = surface area, ΔT = temperature difference l༆  Moving this around, we see that……. L = (λ A Δ T) / Q, or that there is inverse propor?onality btn depth and heat flow i.e. the deeper it is, the longer it takes to freeze l༆  We can therefore use this equa?on to predict how fast ice will build up Forma?on of Snow l༆  This will be reviewed when we get past the psychrometric chart work but while seems obvious to assume that when water vapour rises into the sky and reaches its dew point, and that the air temperature is below freezing, that water will freeze…. l༆  But it isn’t always the case l༆  The air needs to be approximately - 40°C for that to occur Supercooling l༆  hgp://www.youtube.com/watch?v=W0fURJg- K0A Supercooling l༆  A liquid is able to exis?ng below freezing and not freeze – something needs to get the process started (a condensa?on nuclei) Water Phase Diagram Crystal Form...
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