https://www.blue-lines.org/home daily 1.0 2026-03-26 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/f0c6aff1-6c1e-46ec-8467-5598ef247566/Courmayor+Italy.jpg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/20d3fb64-dcbc-424f-bb92-d4aa8dc76605/1.png Home 1. Contrails are formed when aircraft fly through very cold and very humid areas (click arrows to see more). https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/e9df64b6-40f7-4ff5-b463-be5ec87fd262/2.png Home 2. Water vapor from the engine exhaust freezes and turns into long ice clouds in the sky. https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/cfde2d92-d2f9-4837-844d-0731a6551435/3.png Home 3. Some contrails can linger for hours and spread out to become big high-altitude clouds - called cirrus clouds. https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/0432128a-7279-4c81-91d2-803f3aabee06/4.png Home 4. These big cirrus clouds block heat from escaping Earth and keep the atmosphere warm. https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/af34ef4d-8d17-4c53-8300-7bb61444e0dd/5.png Home 5. But if planes avoid the cold and humid areas, they can also avoid making contrails. https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/aa147425-91c5-42ea-a9cc-d8419e6d9775/6.png Home 6. If we slightly redirect 1 in 20 flights, we can eliminate 1-2% of global warming. https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/5dfd7fa7-4f40-4628-81de-06a50effd1ff/IMG_1799.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/502d6c9c-e4a2-427f-b04e-69804ad2cd1a/IMG_2969.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/895e25d6-41ac-48c4-bb36-20074f7decb4/IMG_3983.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/28d227a0-6a65-4369-a043-f6566e9292ed/IMG_4105.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/2db9e817-cb66-4b6d-b2a7-396c32f8d6e1/IMG_4731.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/76679267-21b9-42da-bbf3-6b44ee21305d/IMG_4736.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/9db728ed-ed98-490a-a455-a653acb87b88/Contrails+over+SF.jpeg Home https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/5b23ef33-e31b-4d9b-bafc-675af27f9d32/Photo+headlines.png https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/842e67b7-27fb-49ae-9baa-755cc786187f/Blue+logo+no+date.jpg https://www.blue-lines.org/knowledgehub daily 0.75 2026-03-12 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/895e25d6-41ac-48c4-bb36-20074f7decb4/IMG_3983.jpeg Knowledge hub https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/4a854e5f-5987-4386-9213-329af1c6136f/Contrail+near+original+size.jpeg Knowledge hub https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/1686840264253-WJ61BUQFENVIMEWN1JCN/52975240466_51c4b6d105_h.jpg Knowledge hub https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/addd6f2a-0a19-4134-82d7-8c98d0d6d669/IMG_2969.jpeg Knowledge hub https://www.blue-lines.org/airline-index daily 0.75 2026-03-12 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/323804a0-fa90-4178-82f7-fb7d7ad0c410/Screenshot+2025-11-02+at+8.55.25%E2%80%AFPM.png https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/e1d04fd7-26a1-4500-8a33-f794d5e16d9b/Screenshot+2025-11-02+at+8.53.16%E2%80%AFPM.png https://www.blue-lines.org/contact daily 0.75 2023-08-21 https://www.blue-lines.org/terms-and-privacy daily 0.75 2023-08-21 https://www.blue-lines.org/about daily 0.75 2025-01-23 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/41c5eba1-671a-4525-9ffa-56a7921f2bdf/Contrail+near.jpg https://www.blue-lines.org/facts daily 0.75 2025-11-15 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/e3250197-f232-4323-a8f2-a1e6662e11dc/contrail+chirag-saini-xPysBGe1JCU-unsplash.jpg https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/649939eb-fb41-4118-94df-f47a5cf6e73f/cirrus+clouds+with+plane+and+contrails+nick-tsinonis-pyYTMUVVHtM-unsplash.jpg https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/0468f89a-44d3-41ec-b9c3-607059dbd18b/plane+with+contrail.jpg https://www.blue-lines.org/explore daily 0.75 2025-11-15 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/1686840264253-WJ61BUQFENVIMEWN1JCN/52975240466_51c4b6d105_h.jpg https://www.blue-lines.org/newsletter daily 0.75 2025-11-15 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/2b275d66-c37b-4ed4-b366-96c4f94423f8/Contrails+photo%2C+to+be+credited+Erling+Maartmann-Moe+let+him+know+when+used.jpg https://www.blue-lines.org/who-is-who daily 0.75 2025-11-15 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/fa19dea5-5b56-44f2-8303-d7953bef118e/jeshoots-com-mSESwdMZr-A-unsplash.jpg https://www.blue-lines.org/regulation daily 0.75 2025-11-15 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/eaaae3eb-cdbb-446a-b446-9c3fabcf0d43/A+NASA+satellite+captures+contrails+in+the+skies+over+the+Yellow+Sea%2C+between+mainland+China+and+the+Korean+peninsula%2C+on+January+24%2C+2020.+%28NASA%29+.jpg https://www.blue-lines.org/what-you-can-do daily 0.75 2023-09-26 https://www.blue-lines.org/history daily 0.75 2025-11-15 https://images.squarespace-cdn.com/content/v1/648a2055e6c09960043bad2c/29d487ad-46b0-44e1-b73b-1a6b6173218f/This+photo+was+taken+over+Emden%2C+Germany%2C+on+September+27th%2C+1943%2C+by+Stanley+M.+Smith..jpg https://www.blue-lines.org/arline-excuses daily 0.75 2025-11-15 https://www.blue-lines.org/trials daily 0.75 2026-04-03