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Importance of solar radiation, humidity, evapotranspiration

Short answer

Solar radiation provides energy to drive evaporation, winds and melt. Relative humidity controls evaporation demand and cloud formation. Evapotranspiration returns most precipitation to the atmosphere, governing water balance, crop water need and reservoir loss.

Briefly explain the importance of solar radiation, relative humidity, evapotranspiration in relation to the hydrologic cycle.

  • Solar radiation: It is the source of energy that drives the hydrologic cycle. It evaporates water from oceans and land, heats the air to create winds and convective storms, and melts snow and glaciers (important for Himalayan rivers). The rate of evaporation and transpiration mainly depends on the radiation received.
  • Relative humidity: It is the ratio of actual to saturation vapour pressure of the air. It governs how much more vapour the air can take: low humidity gives a large vapour pressure deficit and high evaporation, while at 100% humidity evaporation stops. It also controls cloud formation, condensation and the amount of precipitation.
  • Evapotranspiration: The combined loss of water by evaporation from soil and water surfaces and by transpiration from plants. It returns about two-thirds of land precipitation to the atmosphere. It is the largest loss in the water balance, decides crop water requirement, reservoir loss and catchment yield, and links the surface water with the atmosphere in the cycle.

✓ Answer checked by Claude Sonnet 5.5

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