# Essay T-φ gram

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T-φ gram Determination of Unreported Meteorological Quantities from T-φ gram 1. Mixing Ratio (W):- It is the ratio of the mass of water vapour to the mass of dry air containing the vapours at a certain temperature. It is expressed in gm/kg. On T-φ gram from dew point temperature we follow isohygric doted green line and read the value at the base. (It can be calculated at all levels where dew point temperature is available). 2. Saturation Mixing Ratio (Ws) :- Mixing ratio at saturation point is called saturation mixing ratio. On T-φ gram from dry bulb temperature we follow isohygric doted green line and read the value at the base. (It can be calculated at all levels where dry bulb temperature is available). 3.…show more content…
On T-φ gram, we follow pseudoadiabate from L.C.L. which cuts the temperature curve at 2 points. The 1st point is L.F.C. and 2nd point is equilibrium level. 14. Negative Area (Stable area): The area enclosed by temperature line, dry adiabate and pseudo-adiabate from surface to L.F.C. is called negative area. It is also called stable area because in this area environment lapse rate is always less than the dry adiabate lapse rate (D.A.L.R.) and pseudo-adiabatic lapse rate. In this area temperature curve always lies to the right of dry adiabate and moist adiabates. 15. Positive Area: The area enclosed by temperature line and moist adiabate between L.F.C. and equilibrium level is called positive area. It is also called unstable area because Environment Lapse Rate (E.L.R.) is always greater than moist adiabatic lapse rate (S.A.L.R). In this area temperature curve always lies to the left of moist adiabate. 16. Virtual Temperature : It is defined as the temperature which the dry air should have in order to be of the same density as the moist air at a given pressure. It is a ficticious temperature and its value is slightly greater than the original temperature. TV = T + W/6 where W is mixing ratio. 17. Equivalent Temperature (TC):- It is the temperature a parcel of air would have if all its latent heat were converted to sensible heat by means of a