Therefore, less of the sun's energy is able to reach the earth's surface, which causes the earth to heat up more slowly. This leads to cooler temperatures. Forecast Tip: When forecasting daytime temperatures, if cloudy skies are expected, forecast lower temperatures than you would predict if clear skies were expected. This relationship is known as cloud-climate feedback. Clouds affect the climate and changes in the climate affect clouds.
This relationship is called cloud-climate feedback. To understand clouds and their effect on climate, we also have to better understand the whole atmosphere. Scientists who try to predict changes in the climate are trying to understand the complex role of clouds in our atmosphere as they figure out how Earth is changing. Several NASA satellites are collecting information about clouds. Skip to content. Louisville Metro. Gas Prices. Derby City Weekend.
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There are now a number of global cloud datasets and datasets available from special field experiments. A thorough study of all these data will take many years and will lead, of course, to new experiments; but the investigations have already provided fresh insights into how clouds might change with climate and provided us with some statistics about the global distribution and character of clouds.
Data collection and model development proceed at GISS in parallel, with the goal of formulating an increasingly precise understanding of how sensitive the climate is in response to external forces and what those changes look like regionally. If we can understand these processes well enough, we may be able to predict the climate of the near-future with sufficient accuracy to be useful for societal planning. Clouds have always been signs of the weather to come.
Scattered white cumulus clusters sailing across a field of blue promise a dry summer afternoon. Massive dark thunderheads portend crop-damaging wind and rain.
A blanket of light gray signals a temperate winter's night. A high sheet of see-through wisps signals a change in the weather tomorrow or the next day. Today meteorologists scan the moving cloud patterns in satellite images to give daily weather forecasts with much greater accuracy than ever before. Special attention to severe weather events like tornadoes with satellite and radar networks has significantly increased the warning time, saving lives. Thus it is ironic that when it comes to forecasting the climate several decades ahead, clouds mainly obscure our vision.
Their most important roles in climate are to modulate Earth's basic radiation balance and to produce precipitation. The law of conservation of energy requires that the energy absorbed by the Earth from the sun balance the energy radiated by the Earth back into space. Clouds both reflect incoming sunlight and inhibit the radiation of heat radiation from the surface, thereby affecting both sides of the global energy balance equation.
Clouds also produce precipitation from water vapor, releasing heat to the atmosphere in the process evaporation of water vapor from the surface cools it, so that these two processes serve to transfer heat from the surface to the atmosphere. Thus, any changes in clouds will modify the radiative energy balance and water exchanges that determine the climate. The trouble is that clouds are produced by the climate, specifically the atmospheric motions winds that are produced by the radiative and latent heating influenced by clouds.
This connected loop of relations is called a feedback loop. The ways that clouds respond to changes in the climate are so complex that it is hard to determine their net effect on the energy and water balances and to determine how much climate might change. What makes it so important to disentangle the interactions of clouds and climate? The balance between absorbed solar radiation and emitted heat radiation sets the temperature of Earth.
For example, when heat radiation from the surface slows, as caused by increasing greenhouse gas abundances, the balance can only be maintained if the temperature rises. Changing clouds can alter this relation, either increasing or decreasing the magnitude of the resulting temperature increase. Also, when clouds change, precipitation will change, which will affect the supply of freshwater to the land where we live and grow our food. Right now, we do not know how important the cloud-radiative or cloud-precipitation effects are and can not predict possible climate changes accurately.
To illustrate the complex linkages that clouds are involved in, the figure below represents the climate system as a three-layer atmosphere and a one-layer ocean stretching from the equator palm tree to the pole snow flake. Clouds occur in the lower two atmospheric layers that comprise the troposphere extending from the surface to about 12 km altitude.
The uppermost atmospheric layer extends from about km and is comprised, going upward, of the stratosphere containing the ozone layer , the mesosphere and the thermosphere. The fluxes of radiation and water are indicated by different types of arrows: sunlight red straight arrows , terrestrial heat radiation blue-striped straight arrows , heat carried by atmospheric and oceanic circulations checkered arrows , water evaporating from the ocean land surface green wiggly arrows and returning to the surface as precipitation broken-blue wiggly arrows , water vapor carried by the atmospheric circulation green wiggly arrows , and freshwater carried by the oceanic circulation purple wiggly arrows.
The primary energy exchange pathway within Earth's climate system begins withsolar heating of the ocean and land surface concentrated towards the equator, continues with transfer of this heat to the atmosphere by the water cycle ocean and land surface coolingby evaporation of water and atmospheric heating by precipitation, and ends with atmospheric cooling by emission of infrared radiation to space.
Because the heating of the ocean and atmosphere is not uniform over the Earth, circulations are caused in both that transport heat and water: in particular, heat is transported by both the ocean and atmosphere away from the equator and towards the poles. Thus, the concentration of solar heating near the equator is not completely balanced by heat radiation and more heat radiation leaves Earth near the poles than arrives from the sun. The existence of these energy and water transports by the atmosphere and ocean means that the energy and water exchanges by other means do not balance locally.
The atmospheric circulation also produces clouds that modulate both the solar radiation gain and infrared radiation loss and are the locus of precipitation formation, establishing a set of intricately linked feedbacks on any forced climate change. An important consequence of these cloud effects is that time scale for the variation of the energy and water exchanges set by the atmosphere through cloud modulations has a time scale that is very different from the time scale on which the ocean can respond.
Thus, the energy and water exchanges also fail to balance over shorter time periods, resulting in unforced variations ofthe climate. Storage of water on land and in ice also contributes to these variations.
Study of the climate system to understand its behavior and its sensitivity to imposed perturbations necessarily entails consideration of all these energy and water exchanges, which constitute the main rapid feedbacks. Moreover, these processes create unforced climate variability that also must be understood to separate them from climate changes that might be caused by human activities. None of these energy and water exchanges can be understood without consideration of the effects of clouds on them, so quantitative cloud data, complemented by precipitation, water vapor, and radiative flux data, are required to diagnose these exchanges and their space-time variations.
At the heart of the difficulty of understanding how clouds affect climatic change is that clouds both cool and heat the planet, even as their own properties are determined by the cooling and heating current link.
The cooling effect is literally visible: the minute water or ice particles in clouds reflect between 30 and 60 percent of the sunlight that strikes them, giving them their bright, white appearance.
Deep bodies of water, such as lakes and oceans, absorb more sunlight than they scatter and so appear very dark. If all of the cloud water in the atmosphere were placed on the surface, the layer depth would only be 0. If all the water vapor in the atmosphere were reduced to a liquid water layer on the surface, the depth would be about 2 cm on average.
A cloudless Earth would absorb nearly 20 percent more heat from the sun than the present Earth does. Thus, clouds can cool the surface by reflecting sunlight back into space, much as they chill a summer's day at the beach.
The cooling effect of clouds is partly offset, however, by a blanketing effect: cooler clouds reduce the amount of heat that radiates into space by absorbing the heat radiating from the surface and re-radiating some of it back down.
The process traps heat like a blanket and slows the rate at which the surface can cool by radiation. Thus, clouds can heat the surface by inhibiting radiative heat loss, much as they warm a winter's night.
One can calculate that a higher surface temperature would result from the buildup of greenhouse gases in the atmosphere and the consequent slowing of heat radiation from the surface, provided nothing else changes. But what happens to the radiation balance if, as part of the climatic response, the clouds themselves change? If the radiative cooling effect of clouds increases more than the heating effect does, the clouds would reduce the magnitude of the eventual warming.
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