The slow cooling of saturated air at 5°C/ km due to latent heat released during condensation. See Lapse Rates
The Demographic Transition Model
The demographic transition model shows the (historical) shift in birth and death rates over time and the consequence population change. The DTM shows a broader categorisation by allocating countries in different stages.
Stage 1 is characterised by the most remote tribes and societies and does not encompass the whole country. It is characterised by fluctuating birth and death rates, both of which are at their highest. Because of this population growth is very low.
The bulk of underdeveloped countries are found in this stage e.g. Zimbabwe, Niger and Bangladesh. It is characterised by a falling death rate and high birth rate. Death rate decline is due to improved nutrition, health practices and services. People are educated on good health practices which lowers the death rate. Conversely, birth rate remain high because of resistance of tribes to change. People tend to listen and comply to ways that cause them to live longer than reducing births. Population growth shots sharply.
Stage 3 is characterised by a falling birth rate. People are obliged to reducing birth rates by contraception and family planning methods. Death rate continue to fall and population growing. NIC (new industrialised countries) such as Brazil and China are found in this stage.
Birth and Death rates remain low fluctuating steadily. Population growth slowly start to decline. Developed countries such as Japan and Sweden are found in this stage.
(Projected) A low birth rate and high death rate causing population decline . There's rarely a country in this stage but countries such as France and Sweden have shifted into this stage.
Limitations of the DTM
The DTM does not take into account migration which is a huge determinant of population growth.
It neglects varying factors within a country which influence death and death rates. Natural disasters can cause high death rates and the aftermath of wars can cause baby booms. These factors can cause an increase or decrease of the rate being studied in stages it's supposed to fall or increase respectively.
It neglects migration which can increase or decrease the population
There's no time interval between stages. NICs such as Malaysia and South Korea are advancing at a faster rate whilst in less developed countries the advancement is and has been slow. Most LEDCs are still stuck in stage 2.
The model assumes that all countries must follow the stages sequentially which is not always true.
The sharp (rapid) decline in birth rate in stage 3 is not always as fast. Most countries (except where policies to decrease birth rate) show a slow decline in birth rate
Based on European countries.
Leaving out a Stage 5 which most developed countries are or transitioning into.