Neutral Atmospheric Stability: Lapse Rate Explained
Atmospheric stability refers to the tendency of the atmosphere to resist or encourage vertical motion. This stability is assessed by comparing the air's adiabatic lapse rate with the surrounding environmental lapse rate (ELR).
Understanding Neutral Stability
A neutrally stable atmosphere is one where a vertically displaced air parcel, once moved, will neither continue moving upward nor return to its original position. It maintains its displaced altitude.
Lapse Rate Comparison
- Dry Adiabatic Lapse Rate (DALR): The rate at which a dry air parcel cools as it rises due to expansion. This rate is approximately $ 9.8^\circ \text{C/km} $.
- Environmental Lapse Rate (ELR): The actual rate at which the surrounding air temperature decreases with an increase in altitude.
Condition for Neutral Stability
Neutral stability occurs specifically when the Environmental Lapse Rate (ELR) is precisely equal to the Dry Adiabatic Lapse Rate (DALR).
Mathematical Condition: $ \text{ELR} = \text{DALR} $
Therefore, in a neutrally stable atmosphere, the lapse rate is equal to the dry adiabatic lapse rate.
Important Questions from Physical Meteorology
- The maximum amount of water vapour which air can hold depends on
- Match the atmospheric optic phenomenon with the causative processes
A. Rainbows P. Refraction B. Mirage Q. Refraction and Reflection C. Corona R. Refraction, Reflection, Dispersion in ice crystals D. Halo S. Diffraction - The wavelength/colour at which solar radiation peaks is
Air rises from point A to C. At point C it reaches the dew point and begins to descend on the leeward side because it is colder than its surroundings. What will happen to the temperature of the descending air?
Read the following statements about land and sea breeze and choose the CORRECT answer.
I. The land breeze is less extensive both vertically and horizontally than the sea breeze
II. Temperature differences between land and sea are rarely as great at night as in the day time.
