World Meteorological Day celebrates the Sun, the Earth and the Weather

The Sun, the Earth and the Weather is the theme of this year’s World Meteorological Day. It highlights the role of the Sun in delivering the energy that powers all life on Earth and drives the weather, ocean currents, and the hydrological cycle.

World Meteorological Day on 23 March celebrates the anniversary of the convention establishing WMO in 1950 and showcases the essential contribution of the WMO community to the safety and wellbeing of society.

National Meteorological and Hydrological Services provide expertise and services both to harness the power of the Sun and to protect us from it. These include 24/7 weather observations and forecasts, as well as monitoring of atmospheric greenhouse gases, ultraviolet radiation, aerosols and ozone and their consequent effects on people, climate, air and water quality and marine and terrestrial life.

Sunlight plays a pivotal role in human health and well-being. Too little Sun impacts our mood and well-being and increases the risk of Vitamin D deficiency.

Greenhouse Effect

Located nearly 150 million kilometres from the Earth, the sun is the heart of our solar system and keeps our planet warm enough for living things to thrive. For over 4.5 billion years, this hot ball of glowing plasma has been the driving force behind weather, climate and life on Earth.

About half the sunlight reaching Earth’s atmosphere passes through the air and clouds to the surface, where it is absorbed and then radiated upward in the form of infrared heat. Much of this heat is absorbed by the greenhouse gases and radiated back in all directions, warming the surface of the Earth and the lower atmosphere.

Without this natural greenhouse effect, the Earth’s average surface temperature would be an inhospitable -18 degrees Celsius (0 °F) instead of the approximately 14 degrees Celsius (59 °F) we experience today.

Solar Energy

The sun provides us with a valuable tool for climate change mitigation in the form of solar energy, which is becoming cheaper and more widely available and has the potential to replace fossil fuels like coal or oil as a major source of electricity. Energy can be harnessed directly from the sun, even in cloudy weather. Solar energy is increasingly popular for generating electricity and heating and desalinating water. Renewable energy, including solar energy, has become the technology of choice, making up almost two-thirds of global capacity additions to 2040 thanks to falling costs and supportive government policies. This is transforming the global power mix, with the share of renewables in generation rising from 25% today to over 40% by 2040, according to the International Energy Agency.

Ozone Layer

Action to protect the stratospheric ozone layer, which protects humans from dangerous ultraviolet and other forms of radiation from the Sun, shows the benefits of concerted international commitment.

In the mid-1980s it was discovered that the ozone shield was being depleted well beyond natural processes as a result of chlorine and bromine atoms coming into contact with ozone and destroying ozone molecules.

The discovery of the ozone hole led to international action to phase out the most damaging chemicals such as chlorine-releasing chlorofluorocarbons (CFCs), used in in refrigeration and air conditioning, and bromine-releasing halons, used as fire-extinguishing agents. Thanks to measures taken under the Montreal Protocol on Substances that Deplete the Ozone Layer, the destruction of the stratospheric ozone layer has been halted.

Original source: WMO
Published on 19 March 2019