1. EXLAIN THE CONCEPT OF TEMPERATURE LAPSE RATE AND EXAMINE ITS IMPORTANCE IN THE UNDERSTANDING OF DIFFERENT WEATHER CONDITIONS.
Environmental lapse rate is a phenomenon of decrease of temperature with an increase in height within the troposphere. It is also called Normal lapse rate. The rate which temperature decreases with height is about 0.65°c for every 100m or 6.5°c depending on the type of air mass, season of the year and atmospheric humidity.
Adiabatic lapse rate is in other words known as adiabatic heating and cooling of the atmosphere. Adiabatic heating and cooling or Adiabatic lapse rate refers to changes in temperature as a result of heating by compression or cooling by expansion. A parcelof air can gain heat when it sinks, desc
ends and contracts. As well as it can equally loose heat when it rises, ascends and expands. Therefore air looses or gains heat as a result of rising and expanding or sinking and contracting. Here, no heat is gain from external sources hence its named Adiabatic ( internal changes). When a parcel of air move upward, it is affected by low pressure as it expands, stretches and become wider, while air moving downward is affected by high pressure as it contracts and is being heated by compressing.
There are two types of Adiabatic lapse rate that is;
Dry Adiabatic lapse rate and Saturated Adiabatic lapse rate.
Dry Adiabatic lapse rate is the rate at which unsaturated air cools through the troposphere as a result of rising and expanding. Dry adiabatic lapse rate cools approximately 10°C every 100m.
saturated Adiabatic lapse rate is the rate at which saturated air cools as a result of upward movement of air cooling at a longer period at which dew point is reached and condensation takes place. SARL can vary because the warmer the air the more moistuire it can hold. as such cooling at slower rate than unsaturated air or dry air. It should be noted that during cooling of saurated air, a great amount of latent heat is being released. The SALR may cool as low as 4°c / 1000m and as high as 9°c/ 1000m. It averages about 5.4°c / 1000m, should temperatures fall below 0°c, as such ttemperature fall below freezing Adiabnatic lapse rate as can be seen below