T-φ gram Essay

1458 Words Oct 23rd, 2013 6 Pages
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.
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On T-φ gram first we find L.C.L. of that level. Then we follow moist adiabate upto the level where moist adiabate and dry adiabate are parallel. Then from this point we follow dry adiabate to the original pressure.

18. Equivalent Potential Temperature (Oe) It is the temperature a parcel of air would have if it were taken from its equivalent temperature to a pressure of 1000mb dry adiabatically.

On T-φ gram, we follow dry adiabate from equivalent temperature to a pressure of 1000mb level.

19. Potential Temperature (Ø): It is the temperature a parcel of air would attain if brought dry adiabatically to a pressure of 1000mb.

20. Mathematically it is expressed as follows: Ø = T (1000/P) .287 Where T & P are the temperature and pressure of the given level whose potential temperature is to be calculated.

On T-φ gram, we follow dry adiabates from given state of T&P to a level of 1000mb.

21. Inversion: The increase in temperature with height in a certain layer of atmosphere is called Inversion.

On T-φ gram it is the temperature curve where temperature is increasing with height. Uses : (1) The lower layer does not go upward. (2) It is due to the formation of clouds (increasing of comparative) (3) Low level inversion is important for the formation at fog. (4) It also shows different air masses.

22. Tropopause: It is the layer of the atmosphere where temperature does not change with height i.e. remain

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