Rain | Definition & Facts

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href="https://www.britannica.com/science/rain/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/rain">Related Topics</a> </div> <div class="tlr-media-slider pb-10 mb-30"> <a class="section-header link-gray-900 font-serif font-14 font-weight-bold mb-10 mx-10" href="https://www.britannica.com/science/rain/images-videos">Images & Videos</a> <div class="slider js-slider position-relative d-inline-flex align-items-center mw-100 "> <div class="slider-container js-slider-container overflow-hidden d-flex overflow-hidden text-nowrap ml-15"> <a href="https://cdn.britannica.com/65/123865-050-687A9E4C/Rain.jpg" data-href="/media/1/489827/118050" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/65/123865-004-7C2224FD/Rain.jpg" alt="rain" height="50" /> </a> <a href="/video/How-Much-Does-a-Cloud-Weigh/280972" data-href="/media/1/489827/280972" class="media-overlay-link d-inline-block mr-5"> <div 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The northern boundary of the 500-mm isohyet (a line on a map connecting points experiencing the same rainfall amount) approximates the maximum advance of the West African summer monsoon." height="50" /> </a> <a href="https://cdn.britannica.com/54/57854-004-772C95F4/distribution-rainfall.jpg" data-href="/media/1/489827/50330" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/54/57854-004-772C95F4/distribution-rainfall.jpg" alt="Global distribution of mean annual rainfall (in centimetres)." height="50" /> </a> <a href="https://cdn.britannica.com/99/102499-004-1609ABAF/Graph-monsoon-rainfall-India-trend-percentages-amounts-1981.jpg" data-href="/media/1/489827/107945" class="media-overlay-link d-inline-block mr-5"> <img loading="lazy" src="https://cdn.britannica.com/99/102499-004-1609ABAF/Graph-monsoon-rainfall-India-trend-percentages-amounts-1981.jpg" alt="Graph of monsoon rainfall in India, 1871–1981. 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They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2025-02-13T00:00:00CST" >Feb 13, 2025</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/science/rain/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Key People: </dt> <dd><a href="/biography/John-Dalton" topicid="150287">John Dalton</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Related Topics: </dt> <dd><a href="/science/cloudburst" topicid="2081822">cloudburst</a></dd> <dd><a href="/science/drizzle" topicid="171725">drizzle</a></dd> <dd><a href="/science/raindrop" topicid="489911">raindrop</a></dd> <dd><a href="/science/freezing-rain" topicid="218756">freezing rain</a></dd> <dd><a href="/science/shower" topicid="541975">shower</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/rain"> See all related content </a> </div> </div> </div> </div><div class="bg-gray-50 p-15 rounded module-spacing recent-news d-flex flex-column float-false"> <div> <h2 class="font-weight-bold font-14 m-0 d-inline"> News <span class="text-gray-600">•</span> </h2> <div class="recent-news-item first-recent-news-item d-inline"> <a class="font-14 gtm-ap-news-link" href="/news/489827/d00f3bf4f37d073d16dabef98197597e" rel="nofollow">Californians brace for flooding in areas torched by wildfires as freezing rain, snow aim for Oregon</a> <span class="font-14 text-gray-600"> <span>•</span> Feb. 13, 2025, 11:21 AM ET (AP) <button class="btn btn-link d-inline p-0 font-12 js-toggle-recent-news"> <span class="text-gray-500">...</span><span>(Show more)</span> </button> </span> </div> </div> <div class="rest-of-recent-news-items"> <div class="recent-news-item mt-5"> <a class="font-14 gtm-ap-news-link" href="/news/489827/85c9d5ecb84d9a37d909fcffaacc68bb" rel="nofollow">Rain douses wildfires in Southern California without causing serious mudslides</a> <span class="font-14 text-gray-600"> <span>•</span> Jan. 27, 2025, 8:10 PM ET (AP) </span> </div> <div class="recent-news-item mt-5"> <a class="font-14 gtm-ap-news-link" href="/news/489827/93b6a9d46d021ba6200030a55ce1d6c8" rel="nofollow">Southern California rain helps firefighters but creates risk of flooding and toxic ash runoff</a> <span class="font-14 text-gray-600"> <span>•</span> Jan. 26, 2025, 10:02 PM ET (AP) </span> </div> <button class="js-toggle-recent-news d-flex btn btn-unstyled font-14 pr-10 rounded-sm mt-10" aria-label="Toggle additional news items"> Show less <em class="material-icons" data-icon="expand_less"></em> </button> </div> </div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref259262"></span>rain</strong>, precipitation of liquid <a href="https://www.britannica.com/science/water" class="md-crosslink " data-show-preview="true">water</a> drops with <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="diameters" href="https://www.britannica.com/dictionary/diameters" data-type="EB">diameters</a> greater than 0.5 mm (0.02 inch). When the drops are smaller, the precipitation is usually called <span id="ref259263"></span><a href="https://www.britannica.com/science/drizzle" class="md-crosslink " data-show-preview="true">drizzle</a>. <em>See also</em> <a href="https://www.britannica.com/science/precipitation" class="md-crosslink " data-show-preview="true">precipitation</a>.</p><span class="marker MOD1 mod-inline"></span><span class="marker PREMOD2 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="280972" data-asm-type="video"><div class="md-assembly-wrapper card-media" data-type="video" video-id="240883"><a data-id="240883" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/How-Much-Does-a-Cloud-Weigh/-280972"><img src="https://cdn.britannica.com/83/240883-138-22889809/How-Much-Does-a-Cloud-Weigh.jpg?w=800&h=450&c=crop" alt="How do clouds float?" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/ILFdOrkO.m3u8" } ], "image": "https://cdn.britannica.com/83/240883-138-22889809/How-Much-Does-a-Cloud-Weigh.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/ZbzRNmoA", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/mja76y6M.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="240883">How do clouds float?</span><span>And how much does a cloud weigh?</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/rain/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph">Concentrations of <span id="ref259264"></span><a href="https://www.britannica.com/science/raindrop" class="md-crosslink ">raindrops</a> typically range from 100 to 1,000 per cubic m (3 to 30 per cubic foot); drizzle droplets usually are more numerous. Raindrops seldom have diameters larger than 4 mm, because as they increase in size they break up. The concentration generally decreases as diameters increase. Except when the rain is heavy, it does not reduce visibility as much as does drizzle. Meteorologists classify rain according to its rate of <a href="https://www.britannica.com/science/autumn-season" class="md-crosslink autoxref " data-show-preview="true">fall</a>. The hourly rates relating to light, moderate, and heavy rain are, respectively, less than 2.5 mm, 2.8 to 7.6 mm, and more than 7.6 mm.</p><span class="marker MOD2 mod-inline"></span><span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Raindrops may form by the coalescence of small water droplets that collide or from the melting of snowflakes and other <a href="https://www.britannica.com/science/ice" class="md-crosslink autoxref " data-show-preview="true">ice</a> particles as they fall into warm <a href="https://www.britannica.com/science/air" class="md-crosslink autoxref " data-show-preview="true">air</a> near the ground.</p><a class="link-module shadow-sm d-block qa-quiz-module" href="/quiz/weather-words-vocabulary-quiz" data-link-module-iframe-link=""> <img loading="lazy" src="https://cdn.britannica.com/73/243573-131-4B037B06/umbrella-rainbow-black-umbrellas-rain.jpg" alt="Umbrella colored like a rainbow sticking out above a sea of black umbrellas while it rains. (storm, weather)" class="rounded-sm mr-15" width="70" /> <div class="line-clamp clamp-5"> <div class="module-title bg-green">Britannica Quiz</div> <div class="font-weight-semi-bold mt-5">Weather Words Vocabulary Quiz</div> </div> </a><span class="marker MOD3 mod-inline"></span><span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph"><span id="ref101593"></span><a href="https://www.britannica.com/place/Mount-Waialeale" class="md-crosslink " data-show-preview="true">Mount Waialeale</a>, <a href="https://www.britannica.com/place/Hawaii-state" class="md-crosslink autoxref " data-show-preview="true">Hawaii</a>, with a 20-year annual average of 11,700 mm (460 inches) from tropical easterlies, is the wettest known point on the <a href="https://www.britannica.com/place/Earth" class="md-crosslink autoxref " data-show-preview="true">Earth</a>. The nearest competitor is <span id="ref101594"></span><a href="https://www.britannica.com/place/Cherrapunji" class="md-crosslink " data-show-preview="true">Cherrapunji</a>, <a href="https://www.britannica.com/place/Meghalaya" class="md-crosslink autoxref " data-show-preview="true">Meghālaya</a>, with an annual average of 11,430 mm from the moist tropical <a href="https://www.britannica.com/science/monsoon" class="md-crosslink autoxref " data-show-preview="true">monsoon</a>. Less than 250 mm and more than 1,500 mm per year represent approximate extremes of rainfall for all of the continents. Rainfall is slight in the central regions of the subtropical anticyclones, which are therefore the <a href="https://www.britannica.com/science/desert" class="md-crosslink autoxref " data-show-preview="true">desert</a> regions of the Earth. In parts of the desert no appreciable rain has ever been observed.</p><div class="one-good-fact-module"> </div><span class="marker MOD4 mod-inline"></span><span class="marker PREMOD5 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="306620" data-asm-type="video"><div class="md-assembly-wrapper card-media" data-type="video" video-id="257490"><a data-id="257490" class="gtm-assembly-link d-flex justify-content-center" style="--aspect-ratio: 16/9" href="/video/what-is-cloud-seeding/-306620"><img src="https://cdn.britannica.com/90/257490-138-6400762C/what-is-cloud-seeding.jpg?w=800&h=450&c=crop" alt="What is cloud seeding and can it be used to fight climate change?" loading="lazy"><script type="application/json"> { "sources": [ { "file" : "//content.jwplatform.com/manifests/21PPUd1i.m3u8" } ], "image": "https://cdn.britannica.com/90/257490-138-6400762C/what-is-cloud-seeding.jpg" ,"tracks": [ { "file" : "//assets-jpcust.jwpsrv.com/tracks/r6sC0cKk.vtt", "label": "English" } ] ,"adfile": "//content.jwplatform.com/manifests/9BLgjNSY.m3u8" } </script><div class="btn btn-xl btn-white btn-circle position-absolute shadow" style="top: 50%; transform: translateY(-50%)"><em class="material-icons" data-icon="play_arrow"></em></div></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><span class="md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption" video-control="257490">What is cloud seeding and can it be used to fight climate change?</span><span>Cloud seeding can produce an extra 5 to 15 percent of precipitation over the course of a season.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div><a class="font-14 mt-10 d-inline-block" href="/science/rain/images-videos">See all videos for this article</a></figcaption></figure></div></div><p class="topic-paragraph">Over most of <a href="https://www.britannica.com/place/Europe" class="md-crosslink autoxref " data-show-preview="true">Europe</a>, <a href="https://www.britannica.com/place/South-America" class="md-crosslink autoxref " data-show-preview="true">South America</a>, eastern <a href="https://www.britannica.com/place/North-America" class="md-crosslink autoxref " data-show-preview="true">North America</a>, and central Africa, the annual rainfall <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="exceeds" href="https://www.britannica.com/dictionary/exceeds" data-type="EB">exceeds</a> 500 mm (20 inches), while over most of <a href="https://www.britannica.com/place/Asia" class="md-crosslink autoxref " data-show-preview="true">Asia</a>, excluding <a href="https://www.britannica.com/place/India" class="md-crosslink autoxref " data-show-preview="true">India</a>, Tibet, and China, the annual rainfall is less than 500 mm, being less than 250 mm in a long tongue extending from Arabia across to northeast Mongolia. The central regions of <a href="https://www.britannica.com/place/Australia" class="md-crosslink autoxref " data-show-preview="true">Australia</a>, most of northern and a part of southwest Africa, portions of the intermontane area of the <a href="https://www.britannica.com/place/United-States" class="md-crosslink autoxref " data-show-preview="true">United States</a>, and portions of the west-central coast and southern east coast of South America also have less than 250 mm of rain in the year. Portions of the western coast of Africa, between the <a href="https://www.britannica.com/place/Equator" class="md-crosslink autoxref " data-show-preview="true">Equator</a> and 10° N, a strip of the western coast of India, parts of Assam, a coastal strip of Myanmar (Burma), windward mountain slopes in the <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="temperate" href="https://www.britannica.com/dictionary/temperate" data-type="EB">temperate</a> latitudes of North and South America, and many isolated tropical stations average more than 2,500 mm of rain in the year. Rainfall intensities greater than 30 mm in five minutes, 150 mm in one hour, or 500 mm per day are quite rare, but these intensities on occasion have been more than doubled for the respective durations.</p><span class="marker MOD5 mod-inline"></span></section> <span class="md-signature"><a href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419">The Editors of Encyclopaedia Britannica</a></span><span class="md-signature">This article was most recently revised and updated by <a href="/editor/Meg-Matthias/12593612">Meg Matthias</a>.</span><span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article> </div> </div> </div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":1,"pageId":489827,"pageLength":446,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-133/js/libs/jquery-3.5.0.min.js?v=3.133.9"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-133/dist/topic-page.js?v=3.133.9' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"B","adLeg":"B","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"MEDIUM","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":true} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Rain | Definition & Facts | Britannica