六年级PEP英语雨循环作文求水循环或雨循环的英语作文

六年级PEP英语雨循环作文求水循环或雨循环的英语作文
六年级PEP英语雨循环作文
求水循环或雨循环的英语作文

六年级PEP英语雨循环作文求水循环或雨循环的英语作文
一、
Rain is liquid precipitation,as opposed to other kinds of precipitation such as snow,hail and sleet.Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface.On Earth,it is the condensation of atmospheric water vapor into drops of water heavy enough to fall,often making it to the surface.Two processes,possibly acting together,can lead to air becoming saturated leading to rainfall:cooling the air or adding water vapour to the air.Virga is precipitation that begins falling to the earth but evaporates before reaching the surface; it is one of the ways air can become saturated.Precipitation forms via collision with other rain drops or ice crystals within a cloud.Rain drops range in size from oblate,pancake-like shapes for larger drops,to small spheres for smaller drops.
二、
Rain plays a role in the hydrologic cycle in which moisture from the oceans evaporates,condenses into drops,precipitates (falls) from the sky,and eventually returns to the ocean via rivers and streams to repeat the cycle again.The water vapor from plant respiration also contributes to the moisture in the atmosphere.
A scientific model known as the Bergeron process explains how rain forms and falls.>>
The Bergeron–Findeisen process (after Tor Bergeron and W.Findeisen),also known as the cold rain or ice crystal process,is the formation of precipitation in the cold clouds of the mid and upper latitudes by ice crystal growth.The equilibrium vapor pressure over water is greater than the saturation vapor pressure over ice,at the same temperature.Therefore in a mixed phase cloud,the liquid water will be out of vapor pressure equilibrium and will evaporate to reach equilibrium.The water droplets will move toward the lower pressure over the ice and diffuse onto the ice crystals.The vapor will be condensed and freeze onto the ice crystal,causing it to grow larger.