ATMOSPHERIC SYSTEMS
The EDEXCEL Teachers’ Guide offers the following advice for the areas which are required for the A2 examination.
Key Idea: The Atmosphere is dynamic
Candidates should be aware that the amount of INSOLATION received depends on:
Solar constant
Distance from the sun
Altitude of the sun
Length of day and night
- variations in these factors need to be considered
The impact of absorption, reflection and scattering on GLOBAL HEAT BUDGET should be recognised.
The influence of surplus heat at the equator on the development of circulation cells should be known.
Disruption of FERREL CELL by ROSSBY WAVES and JET STREAM should be recognised.
Influence of PRESSURE GRADIENT FORCE and CORIOLIS FORCE on global wind pattern.
Pattern of pressure belts should be able to be described and explained.
Impact of EL NINO SOUTHERN OSCILLATION on the pattern should be recognised.
Key Idea: Different weather systems cause characteristic weather conditions
Candidates are expected to know the significance of DEW POINT, CONDENSATION LEVEL, SATURATION and RELATIVE HUMIDITY.
Candidates should be able to describe the formation, movement and change of different pressure systems.
Air masses for British Isles need to be known.
Emphasis should be on the weather conditions associated with them. The source region and track are both important.
It should be appreciated that there are variations in the weather associated with differing systems and at different times of year e.g winter and summer anticyclones
An example of a named hurricane.
Key Idea: Human and physical factors affect the atmosphere at a local scale
Candidates need to know how and why lapse rates differ and vary with height. They should be familiar with the plotting of this on a tephigram and how to interpret these. The link with stability and instability should be recognised.
The weather associated with different atmospheric states should be known.
Candidates should be familiar with the instruments of a weather station and how they are used. Units of measurement should be known. The limitations of instruments should be appreciated both in accurately recording and effectively forecasting weather.
Impact of urban area on a range of variables should be understood. One named area should be studied.