Mixing Ratio

[Jon Miller]

I've seen the term ' Mixing Ratio' used in FCST discussions here and elsewhere and have never quite understood its meaning and its significance in severe thunderstorm forecasting ?

Would appreciate any help or info on this subject.

Thanks
Jon Miller
KT8NDO

 

[Paul Knightley]

Hi Jon,

Humidity mixing ratio (HMR) is simply the amount of moisture contained within a parcel of air, expressed as kilograms of water vapour per kilogram of dry air at a given pressure (often, actually, grams per kilogram). Thus, effectively, when the HMR is high for surface parcels, the low-level air is moist, and equates to a higher dew point. As moisture is one of the ingredients for deep moist convection, you can see its importance!