Definitions - j

Jatropha Curcas is a bio-fuel crop that is being widely touted as a sustainable and more efficient alternative to first generation feed stocks, such as corn and palm oil.

Firms seeking to commercialise the jatropha-based biofuels, argue that the plant delivers high yields of oil and can be grown in marginal areas with low levels of water, limiting the extent to which cultivation would eat into existing agricultural land and water resources.

Rivers of high-speed air in the atmosphere. Jet streams form along the boundaries of global air masses where there is a significant difference in atmospheric temperature. The jet streams may be several hundred miles across and 1-2 miles deep at an altitude of 8-12 miles. They generally move west to east, and are strongest in the winter with core wind speeds as high as 250 mph. Changes in the jet stream indicate changes in the motion of the atmosphere and weather

This is usually defined as the act of replacing stale or noxious air with fresh air.

In the eco field it is also important to differentiate between what are termed passive ventilation and active ventilation. Passive ventilation is where no additional electrical or mechanical energy is required to make the ventilation work. Active ventilation on the other hand won't work without using additional energy.

Passive ventilation is an aspect of passive building design and often utilizes heat chimneys and natural air flows across the land to achieve adequate ventilation.