![\"Snow](\"https:\/\/www.purdue.edu\/fnr\/extension\/wp-content\/uploads\/2015\/05\/Woodlands_Lawson.jpg\")
“When it snows\u2026\nand temperatures drop,
\nThat\u2019s when you\u2019ll hear
\nThe Snap, Crackle and Pop.”<\/p>\n
“When it snows\u2026
\nand temperatures drop,
\nThat\u2019s when you\u2019ll hear
\nThe Snap, Crackle and Pop.”<\/p>\n
Few things can compare to the peacefulness of walking in a forest filled with snow covered trees until you hear a snap, crackle or an explosive \u201cPOP\u201d echoing through the woods. What on earth was that? If the noise is followed by a \u201cwhoosh,\u201d it may be a limb that just broke and crashed to the ground. If it sounded like a gunshot but nobody is there, you may be listening to the sound of a frost crack forming on a tree.<\/p>\n
What are frost cracks?<\/em><\/strong> Water in the plant is under a negative water potential, or in common terms, under tension. In the winter, when deciduous trees have no leaves, the water pressure in the sap becomes positive. A flow occurs where water moves up in the xylem and cycles down in the phloem (food conducting cells). The mechanism of this winter flow in temperate trees is not well understood physiologically. The sap increases in simple soluble sugars as the cold weather begins and increases until midwinter to work like antifreeze, depressing the freezing point of water. This is why maple syrup can be tapped in late winter.<\/p>\n Species with darker colored bark and thinner bark can be affected by frost cracks. Some genotype effects have been found in black walnuts at Purdue. Field conditions and topography that effect cold air movement can affect frost cracks. Most form on the southwestern section of the trunk, the area most affected by warming from sunlight during winter afternoons. Somehow, this conditioning sets up the tree when temperatures plummet to single digits (in Fahrenheit) or lower, especially after a warmer period.<\/p>\n So if you wander through the woods this winter, stop but\u00a0don\u2019t \u201cdrop\u201d when you listen to the sounds of the trees.<\/p>\n “When the snow twinkles Resources<\/strong> Shaneka Lawson, Adjunct Assistant Professor James McKenna, Operational Tree Breeder “When it snows\u2026 and temperatures drop, That\u2019s when you\u2019ll hear The Snap, Crackle and Pop.” Few things can compare to the peacefulness of walking in a forest filled with snow covered trees until you hear a snap, crackle or an explosive \u201cPOP\u201d echoing through the woods. What on earth was that? If the noise is […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[42,44,45],"tags":[60,62,63],"class_list":["post-2761","post","type-post","status-publish","format-standard","hentry","category-forestry","category-gotnatureforkids","category-howto","tag-forestry","tag-got-nature-for-kids","tag-how-to","audience-for-enthusiasts","audience-for-homeowners","audience-for-landowners","audience-for-professionals"],"acf":[],"aioseo_notices":[],"publishpress_future_action":{"enabled":false,"date":"2026-04-21 10:00:26","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/2761","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/comments?post=2761"}],"version-history":[{"count":8,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/2761\/revisions"}],"predecessor-version":[{"id":33572,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/posts\/2761\/revisions\/33572"}],"wp:attachment":[{"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/media?parent=2761"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/categories?post=2761"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.purdue.edu\/fnr\/extension\/wp-json\/wp\/v2\/tags?post=2761"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nNobody knows for sure. You may hear one happen, typically on a cold late winter morning after a warm spell. They sound like muffled to loud rifle shots. Typically, these cracks occur on the south side of the trunk between two and five feet up the tree (when measuring from the ground). With leaves on, water is pulled upwards from tree roots through the xylem vessels by the differences in water potential from the air to the soil and escapes through the leaves (the soil-plant-air continuum).<\/p>\n![\"Forest](\"https:\/\/www.purdue.edu\/fnr\/extension\/wp-content\/uploads\/2015\/05\/ForestCrack.jpg\")
Scientists are challenged to study the phenomena of frost cracks. They involve thousands of xylem vessels in a very narrow vertical line bursting all at once \u2013 as if a line of sap is too low in sugar concentration \u2013 and then freezes hard explosively bursting the vessels. After several growing seasons, most trees will heal over the crack, but callus growth makes them appear wider. Valuable timber logs can still be profitably harvested with frost cracks as millers can cut through them to minimize the defect.<\/p>\n
\nand the skies are bare\u2026
\nTemperatures drop
\nand a chill fills the air.
\nIf you listen real close
\nand adjust your cap,
\nYou just might hear
\na tree go ‘Snap!’\u201d<\/p>\n
\nBark Splitting on Trees<\/a>, Cornell University
\nVideo: How Do Trees Survive Winter?<\/a>\u00a0MinuteEarth
\nWinterize Your Trees\u200b<\/a>, The Education Store<\/p>\n
\nDepartment of Forestry and Natural Resources<\/p>\n
\nDepartment of Forestry and Natural Resources\u200b\u200b\u200b\u200b\u200b<\/p>\n","protected":false},"excerpt":{"rendered":"