Field guide training: Climate and weather – Part 1

This module is intended to provide an introduction to climatology and meteorology for all prospective rangers and field guides. Among other things, the following aspects should be learned: How does the climate in Southern Africa develop, what factors influence it, what is the difference between climate and weather, how are South African summers and winters characterized, what types of clouds are there and what are their characteristics, what types of winds are there and when do they occur? At the beginning, terms will be explained that are important for understanding climatology and meteorology:

Climate vs. weather

Often these two terms are used largely congruently and in fact climate and weather are closely related, but they are not synonyms. While the weather describes the interaction of temperature, solar radiation, wind and humidity at a location within a short period of hours to a few days, the climate is the recording of the various weather conditions at a location over a period of time long enough to determine statistical properties such as mean values, deviations and extreme values. As a rule, the Earth's climate is surveyed over periods of 30 years.

Air pressure/atmospheric pressure

The earth is surrounded by a relatively thin layer of breathing air, which is held near the ground by the gravitational force. The higher you get, the thinner the air. The air pressure results from the weight of the air at a certain point. This weight is generated by the air above this point. The air pressure is indicated by the atmospheric pressure in the unit mbar.

Gravitational force/gravity force

The gravitational force is the force responsible for two masses attracting each other. The further the masses are apart, the weaker they become, but their range is unlimited. An apple that falls to the earth is therefore not only attracted to the earth, but the apple also attracts to the earth. However, the gravitational force of the earth is much stronger, so that the force of the apple does not carry any weight. It is particularly the gravitational force that determines most of the physical processes on our planet: The formation of tides, the flow of water in rivers, precipitation, tectonic plate movements, the rotation of the moon in its orbit around the earth, etc. – all of these are factors that influence the formation of the moon.

Convection

Convection is the circular movement of liquids or gases. This movement often results from a temperature gradient and the resulting differences in density. The transport of warm air in the atmosphere can also be explained by convection. By the way: Water vapour, which is transported in warm air layers, condenses into clouds in higher atmospheric layers.

Dew point

The temperature at which the air is saturated with water vapour is called the condensation temperature. At this temperature the water vapour becomes raindrops.

Pressure gradient force

The pressure gradient force is the geophysical cause for the wind as a compensating flow of air between a high and a low pressure area. The movement is always from the high pressure area to the low pressure area.

Quelle: Hine, Grant & Gilie; Nature Guide Level 1 – Learner Manual; Südafrika; 2014