page_title: Weather satellite
section_title: DMSP
hierarchical_section_title: Weather satellite / Types / Polar orbiting / DMSP
caption_attribution_description: English: A turnstile antenna used for reception of weather satellite data on 137&#160;MHz. It consists of two identical dipole antennas at right angles, fed in quadrature. This type of antenna is used because it receives circularly polarized radio waves transmitted by the satellite. Circular polarization is used for satellite communication because it is insensitive to the relative orientation of the transmitting and receiving antenna elements. Français&#160;: Une antenne tourniquet utilisée pour la réception des données météorologiques par satellite de la bande: 137 MHz 138 MHz. Elle ce compose de deux antennes dipôles identiques à angle droit, alimentées en quadrature. Ce type d'antenne est utilisé parce qu'il reçoit en polarisation circulairement les ondes radio transmises par le satellite. La polarisation circulaire est utilisé pour les communications par satellite car elle est insensible à l'orientation relative de transmission et la réception par les éléments d'antenne.
context_page_description: The weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting, covering the entire Earth asynchronously, or geostationary, hovering over the same spot on the equator.
  Meteorological satellites see more than clouds: city lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, etc. Other types of environmental information are collected using weather satellites. Weather satellite images helped in monitoring the volcanic ash cloud from Mount St. Helens and activity from other volcanoes such as Mount Etna. Smoke from fires in the western United States such as Colorado and Utah have also been monitored.
  El Niño and its effects on weather are monitored daily from satellite images. The Antarctic ozone hole is mapped from weather satellite data. Collectively, weather satellites flown by the U.S., Europe, India, China, Russia, and Japan provide nearly continuous observations for a global weather watch.
context_section_description: The United States Department of Defense's Meteorological Satellite (DMSP) can "see" the best of all weather vehicles with its ability to detect objects almost as 'small' as a huge oil tanker.  In addition, of all the weather satellites in orbit, only DMSP can "see" at night in the visual.  Some of the most spectacular photos have been recorded by the night visual sensor; city lights, volcanoes, fires, lightning, meteors, oil field burn-offs, as well as the Aurora Borealis and Aurora Australis have been captured by this 450-mile-high space vehicle's low moonlight sensor.
  At the same time, energy use and city growth can be monitored since both major and even minor cities, as well as highway lights, are conspicuous.  This informs astronomers of light pollution. The New York City Blackout of 1977 was captured by one of the night orbiter DMSP space vehicles.
  In addition to monitoring city lights, these photos are a life saving asset in the detection and monitoring of fires.  Not only do the satellites see the fires visually day and night, but the thermal and infrared scanners on board these weather satellites detect potential fire sources below the surface of the Earth where smoldering occurs.  Once the fire is detected, the same weather satellites provide vital information about wind that could fan or spread the fires.  These same cloud photos from space tell the firefighter when it will rain.
  Some of the most dramatic photos showed the 600 Kuwaiti oil fires that the fleeing Army of Iraq started on February 23, 1991.  The night photos showed huge flashes, far outstripping the glow of large populated areas.  The fires consumed millions of gallons of oil; the last was doused on November 6, 1991.
caption: Turnstile antenna for reception of 137 MHz LEO weather satellite transmissions
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