air conditioning

AIR:

The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation)

Structure of the atmosphere

Principal layers

In general, air pressure and density decrease with altitude in the atmosphere. However, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions (see the temperature section, below). Because the general pattern of the temperature/altitude profile is constant and recognizable through means such as balloon soundings, the temperature behavior provides a useful metric to distinguish between atmospheric layers. In this way, Earth's atmosphere can be divided (called atmospheric stratification) into five main layers. From highest to lowest, these layers are:

• Exosphere: >700 km (>440 miles)
• Thermosphere: 80 to 700 km (50 to 440 miles)
• Mesosphere: 50 to 80 km (31 to 50 miles)
• Stratosphere: 12 to 50 km (7 to 31 miles)
• Troposphere: 0 to 12 km (0 to 7 miles)

AIR CONDITIONING:

Air conditioning (often referred to as aircon, AC or A/C) is the process of altering the properties of air(primarily temperature and humidity) to more favourable conditions, typically with the aim of distributing the conditioned air to an occupied space to improve comfort. More generally, air conditioning can refer to any form of technology, heating, cooling, de-humidification, humidification, cleaning, ventilation, or air movement, that modifies the condition of air