During the past century through food and energy production, human activities have altered the world's nitrogen cycle by accelerating the rate of reactive nitrogen creation. India has made impressive strides in the agricultural front, in which N fertilizer plays a major role.

Clouds contribute significantly to the formation of many of the natural hazards. Hence cloud mapping and its classification becomes a major component of the various physical models which are used for forecasting natural hazards.

There has been a strong disagreement between model predictions of troposphere warming and observations of temperature trends from radiosondes and satellites. However, when tropospheric temperature reconstructions are generated from thermal-wind measurements and the thermal-wind equation for 1970

Understanding the composition of the atmosphere over geological time is critical to understanding the history of the Earth system, as the atmosphere is closely linked to the lithosphere, hydrosphere and biosphere. Although much of the history of the lithosphere and hydrosphere is contained in rock and mineral records, corresponding information about the atmosphere is scarce and elusive owing to the lack of direct records.

Dust aerosols can suppress rainfall by increasing the number of cloud condensation nuclei in warm clouds and affecting the surface radiation budget and boundary layer instability. The extent to which atmospheric dust may affect precipitation yields and the hydrologic cycle in semiarid regions remains poorly understood. We investigate the relationship between dust aerosols and rainfall in the West African Sahel where the dust-rainfall feedback has been speculated to contribute to sustained droughts.

Nitryl chloride, an active halogen, can be produced through the night-time reaction of dinitrogen pentoxide with chloride-containing aerosol in the polluted marine boundary, and has been measured at levels that are sufficient to affect the photochemistry of oxidants off the southwestern US coast and near Houston, Texas.

Tropospheric ozone contributes significantly to human-induced greenhouse warming. Calculations from satellite measurements of spectral radiance suggest that ozone in the upper troposphere caused an average reduction in clear-sky outgoing long-wave radiation over the oceans of 0.480.14 W m- 2 for the year 2006 between 45