{"id":15818,"date":"2026-06-13T05:17:32","date_gmt":"2026-06-12T23:47:32","guid":{"rendered":"https:\/\/ibexaviation.com\/pilot-training\/?p=15818"},"modified":"2026-07-26T10:43:49","modified_gmt":"2026-07-26T05:13:49","slug":"temperature-measurement-2","status":"publish","type":"post","link":"https:\/\/ibexaviation.com\/pilot-training\/temperature-measurement-2\/","title":{"rendered":"Temperature Measurement"},"content":{"rendered":"<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-1.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<h2>Effect Heat and Temperature of Atmosphere on Weather<\/h2>\n<h3>Heat and Temperature<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-2.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Heat<\/strong> is the total kinetic energy present in the air molecules within a given volume of air.<\/li>\n<li><strong>Specific Heat<\/strong> is the amount of heat required to raise the temperature of a unit mass by <strong>1\u00b0C<\/strong>.<\/li>\n<li>Specific Heat of:\n<ul>\n<li>Water: <strong>1.0<\/strong><\/li>\n<li>Ice: <strong>0.5<\/strong><\/li>\n<li>Soil: <strong>0.2<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Since soil has a lower specific heat than water, land heats up and cools down faster than the sea.<\/li>\n<li><strong>Temperature<\/strong> is the measure of heat in a substance.<\/li>\n<li><strong>Ambient Temperature<\/strong> is the surrounding atmospheric temperature.<\/li>\n<li><strong>Virtual Temperature<\/strong> is the temperature at which dry air would have the same pressure and density as moist air.<\/li>\n<\/ul>\n<h3>Centigrade, Fahrenheit and Kelvin<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-3.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The Celsius and Fahrenheit scales are based on the melting point of ice and the boiling point of water.<\/li>\n<li>On the Celsius scale:\n<ul>\n<li>Melting point of ice = <strong>0\u00b0C<\/strong><\/li>\n<li>Boiling point of water = <strong>100\u00b0C<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Centigrade (\u00b0C) = [5 \u00d7 (F \u2212 32)] \u00f7 9<\/strong><\/li>\n<li><strong>Fahrenheit (\u00b0F) = [(9 \u00f7 5) \u00d7 C] + 32<\/strong><\/li>\n<li>The <strong>Kelvin<\/strong> scale is based on the internal energy contained in matter.<\/li>\n<li><strong>0 Kelvin = \u2212273\u00b0C<\/strong> (Absolute Zero).<\/li>\n<\/ul>\n<h3>Temperature Measurement Instruments<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-4.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Mercury Thermometer \u2013 Measures ambient temperature.<\/li>\n<li>Stevenson Screen \u2013 Used for measuring surface air temperature.<\/li>\n<li>The Stevenson Screen is installed about <strong>4 ft (1.25 m)<\/strong> above the ground in an open area.<\/li>\n<li>Alcohol Thermometer \u2013 Measures minimum and maximum temperatures.<\/li>\n<li>Thermograph \u2013 Provides a continuous record of temperature.<\/li>\n<li>Bi-metal Thermometer \u2013 Measures Outside Air Temperature (OAT) in aircraft.<\/li>\n<li>Radiosonde Balloons \u2013 Used by meteorological departments for upper-air temperature observations.<\/li>\n<li>Satellites \u2013 Used for thermal imaging.<\/li>\n<\/ul>\n<h3>Solar Radiation<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-5.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Radiation<\/strong> is the transfer of heat without the need for a material medium.<\/li>\n<li><strong>Insolation<\/strong> is the incoming solar radiation reaching the Earth&#8217;s surface.<\/li>\n<li>Insolation is inversely proportional to the obliquity (angle) of the Sun&#8217;s rays.<\/li>\n<li>Maximum insolation occurs near the thermal equator.<\/li>\n<li>Minimum insolation occurs near the poles.<\/li>\n<li>Short-wave solar radiation reaches the Earth&#8217;s surface with little absorption by the atmosphere.<\/li>\n<li>Long-wave radiation is partly absorbed by clouds before reaching the Earth.<\/li>\n<\/ul>\n<h3>Albedo<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-6.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Albedo<\/strong> is the reflecting power of the Earth&#8217;s surface.<\/li>\n<li>During clear weather, about <strong>85%<\/strong> of the Sun&#8217;s energy reaches the Earth.<\/li>\n<li>Maximum albedo occurs over snow-covered surfaces.<\/li>\n<li>Minimum albedo occurs over marshy land.<\/li>\n<li><strong>Heat Budget<\/strong> is the balance between radiation received and radiation emitted.<\/li>\n<\/ul>\n<h3>Terrestrial Radiation<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-7.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Terrestrial Radiation<\/strong> is the long-wave radiation emitted by the Earth&#8217;s surface.<\/li>\n<li>The atmosphere is primarily heated by terrestrial radiation.<\/li>\n<li><strong>Greenhouse Effect<\/strong> is the trapping of terrestrial radiation by carbon dioxide and water vapour.<\/li>\n<li><strong>Nocturnal Radiation<\/strong> refers to terrestrial radiation emitted during the night.<\/li>\n<\/ul>\n<h2>Types of Heat Transfer in the Atmosphere<\/h2>\n<h3>Transfer of Heat by Conduction<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-8.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Conduction<\/strong> is the transfer of heat between molecules that are in direct contact.<\/li>\n<li>Conduction mainly occurs near the Earth&#8217;s surface.<\/li>\n<li>During the day, the Sun heats the ground, which in turn warms the adjacent air.<\/li>\n<li>At night, the cooling land cools the air near the surface by conduction.<\/li>\n<\/ul>\n<h3>Transfer of Heat by Convection<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-9.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Convection<\/strong> is the transfer of heat through the vertical movement of air.<\/li>\n<li>Strong solar heating warms the air near the ground.<\/li>\n<li>Warm, lighter air rises while cooler, denser air sinks.<\/li>\n<li>Afternoon cumulus clouds commonly develop due to convection.<\/li>\n<\/ul>\n<h3>Transfer of Heat by Advection<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-10.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Advection<\/strong> is the horizontal transfer of heat by wind.<\/li>\n<li><strong>Warm Advection<\/strong> occurs when warm air moves into a colder region.<\/li>\n<li><strong>Cold Advection<\/strong> occurs when cold air moves into a warmer region.<\/li>\n<\/ul>\n<h3>Latent Heat<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-11.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Water exists in the atmosphere as solid, liquid and gas.<\/li>\n<li><strong>Dry Air<\/strong> contains no water vapour.<\/li>\n<li><strong>Latent Heat<\/strong> is the heat transferred when water changes its physical state.<\/li>\n<li>Latent heat is exchanged whenever water changes between solid, liquid and gaseous forms.<\/li>\n<\/ul>\n<h3>Evaporation, Melting and Sublimation<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-12.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Evaporation<\/strong> is the change of state from liquid to gas.<\/li>\n<li>Evaporation can occur at all temperatures above <strong>\u2212273\u00b0C (Absolute Zero)<\/strong>.<\/li>\n<li>Evaporation increases as temperature increases.<\/li>\n<li><strong>Melting<\/strong> is the change of state from solid to liquid.<\/li>\n<li><strong>Sublimation<\/strong> is the direct change from solid to gas.<\/li>\n<li>Latent heat is absorbed during evaporation, melting and sublimation.<\/li>\n<\/ul>\n<h3>Freezing, Condensation and Deposition<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-13.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Freezing<\/strong> is the change from liquid to solid.<\/li>\n<li>Freezing nuclei are required for water to freeze.<\/li>\n<li>Without freezing nuclei, water may remain as supercooled droplets.<\/li>\n<li><strong>Condensation<\/strong> is the change from gas to liquid.<\/li>\n<li>Condensation nuclei are required for the formation of clouds, fog and dew.<\/li>\n<li>Without condensation nuclei, air becomes supersaturated.<\/li>\n<li><strong>Deposition<\/strong> is the direct change from gas to solid.<\/li>\n<li>Latent heat is released during freezing, condensation and deposition.<\/li>\n<\/ul>\n<h2>Variation of Temperature with Altitude<\/h2>\n<h3>Temperature Lapse Rate<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-14.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The atmosphere is heated from the Earth&#8217;s surface.<\/li>\n<li>Temperature generally decreases with increasing altitude.<\/li>\n<li><strong>Lapse Rate<\/strong> is the rate of temperature change with height.<\/li>\n<li>Under ISA conditions, the lapse rate is <strong>1.98\u00b0C per 1000 ft<\/strong>.<\/li>\n<\/ul>\n<h3>Isothermal and Inversion Layers<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-15.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Temperature does not always decrease with altitude.<\/li>\n<li>An <strong>Isothermal Layer<\/strong> has a constant temperature with height.<\/li>\n<li>An <strong>Inversion Layer<\/strong> has temperature increasing with height.<\/li>\n<\/ul>\n<h3>Types of Inversion<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-16.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li><strong>Radiation Inversion<\/strong> occurs when surface air cools rapidly by conduction during the night while air above remains warmer.<\/li>\n<li><strong>Subsidence Inversion<\/strong> occurs in high-pressure areas where descending air creates an inversion near the surface.<\/li>\n<li><strong>Stratospheric Inversion<\/strong> occurs because ozone absorbs ultraviolet radiation, warming the upper stratosphere.<\/li>\n<\/ul>\n<h2>Effect of Weather and Time of day on Variation of Temperature <\/h2>\n<h3>Diurnal Variation of Temperature<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-21.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Diurnal variation is the change in temperature during a 24-hour period.<\/li>\n<li>Maximum solar radiation occurs around noon.<\/li>\n<li>The highest air temperature usually occurs about <strong>2\u20133 hours after noon<\/strong>.<\/li>\n<li>The minimum temperature generally occurs about <strong>30 minutes to 1 hour after sunrise<\/strong>.<\/li>\n<\/ul>\n<h3>Effect of Clouds on Temperature<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-18.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>During the day, clouds reduce incoming solar radiation, lowering daytime temperatures.<\/li>\n<li>At night, clouds reduce heat loss by trapping terrestrial radiation, resulting in warmer nights.<\/li>\n<\/ul>\n<h3>Diurnal Variation in Cloudy Weather<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-19.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Cloud cover reduces both daytime heating and nighttime cooling.<\/li>\n<li>As a result, cloudy weather produces a smaller daily temperature range.<\/li>\n<\/ul>\n<h3>Diurnal Variation Due to Winds<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-20.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Wind reduces the daily temperature range by mixing air.<\/li>\n<li>During the day, warm surface air mixes with cooler air above.<\/li>\n<li>At night, cold surface air mixes with warmer air aloft.<\/li>\n<li>Coastal areas have a smaller diurnal variation because of land and sea breezes.<\/li>\n<\/ul>\n<h3>Diurnal Variation over Land and Sea<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-21.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The sea has a smaller daily temperature variation than land.<\/li>\n<li>Sea water heats and cools more slowly because of its higher specific heat.<\/li>\n<\/ul>\n<h3>Effect of Latitude on Temperature<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-22.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>All parts of the Earth receive approximately the same amount of solar energy.<\/li>\n<li>At higher latitudes, the Sun&#8217;s rays spread over a larger area, reducing heating per unit area.<\/li>\n<li>Therefore, temperatures decrease with increasing latitude.<\/li>\n<li>The Earth&#8217;s varying distance from the Sun has only a negligible effect on temperature.<\/li>\n<\/ul>\n<h3>Seasonal Variation in Temperature<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-23.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>The Earth&#8217;s axis is tilted by <strong>23.5\u00b0<\/strong> to its orbital plane.<\/li>\n<li>This causes the Sun&#8217;s overhead position to shift during the year.<\/li>\n<li>On <strong>21 June<\/strong>, the Sun is overhead at the Tropic of Cancer, producing summer in the Northern Hemisphere.<\/li>\n<li>On <strong>21 December<\/strong>, the Sun is overhead at the Tropic of Capricorn, producing summer in the Southern Hemisphere.<\/li>\n<\/ul>\n<h3>Effect of Winds on Temperature<\/h3>\n<p>  <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/aviation-meteorology\/m4-temperature-measurement-24.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Winds from warm tropical regions increase local temperatures.<\/li>\n<li>Winds from cold polar regions reduce temperatures.<\/li>\n<li>At night, downslope winds from hills cool valley floors and may produce valley fog.<\/li>\n<li>Hilltops are generally cooler than foothills because the air reaching higher elevations has less contact with the warm ground.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Effect Heat and Temperature of Atmosphere on Weather Heat and Temperature Heat is the total kinetic energy present in the air molecules within a given volume of air. Specific Heat is the amount of heat required to raise the temperature of a unit mass by 1\u00b0C. Specific Heat of: Water: 1.0 Ice: 0.5 Soil: 0.2 Since soil has a lower specific heat than water, land heats up and cools down faster than the sea. Temperature is the measure of heat in a substance. Ambient Temperature is the surrounding atmospheric temperature.&hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"disable_featured_image":false,"footnotes":""},"categories":[358],"tags":[],"class_list":["post-15818","post","type-post","status-publish","format-standard","hentry","category-aviation-meteorology"],"_links":{"self":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/15818","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/comments?post=15818"}],"version-history":[{"count":1,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/15818\/revisions"}],"predecessor-version":[{"id":16677,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/15818\/revisions\/16677"}],"wp:attachment":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/media?parent=15818"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/categories?post=15818"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/tags?post=15818"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}