This thermometer should never be employed with a parted fluid column since it generally leads to incorrect temperature measurements. Liquid-in-glass. “Temperature readings should be noted immediately after removal because a glass thermometer can be affected by the environmental temperature, heat produced by the hand holding it, cleaning, etc. Condition: Good . This type of thermometer was developed by a German based physicist named Daniel Gabriel Fahrenheit. For this purpose, for example, a tube is wrapped into a coil and filled … Mercury was/is used not only because of the wide temperature range (theoretically applicable from -39 °C to 357 °C) but also because mercury hardly wets the glass tube. Diese Cookies sind für die ordnungsgemäße Funktion der Webseite unerlässlich. If the cold junction is kept at a constant known temperature, the galva… As long as your consent is not given, no ads will be displayed. The higher temperature junction is usually called the ‘hot junction’ and the lower temperature junction the ‘cold junction’. They are considered inapt for applications involving extremely high or low temperatures. Equipment: Gas Thermometer demo and Thermometers (assorted). In the case of the ethanol-filled thermometer, the upper limit for measurement is 78 °C (172.4 °F), which makes it useful for measuring daytime, nighttime and body temperatures, although not … Liquid-in-glass thermometers are based on the principle of thermal expansion of substances. A liquid-in-glass thermometer consists of a glass (sometimes quartz) bulb with a glass capillary joined to it. 2. In liquid-in-glass thermometers, the thermal expansion of liquids is used for measuring the temperature! The temperature measurement range of alcohol thermometers varies from 115°C to 785°C, where former is the freezing temperature point of alcohol and latter is boiling temperature point of alcohol. The deflection on the galvanometer G depends on the difference in temperature between junctions X and Y and is caused by the difference between voltages Vx and Vy. 14", 12" and 7.9" General Red Organic Liquid Thermometers GT-Gen-Purpose-Therm. Temperature in a Gas . Organic liquids which are usually employed for construction of liquid-in-glass thermometers include toluene, ethyl alcohol and pentane. They are handy and convenient to use. Save my name, email, and website in this browser for the next time I comment. Unlike electrical thermometers, they do not necessitate power supply or batteries for charging. set up when the junction of two dissimilar metals is heated. Therefore, they must be handled with extra care because they are likely to break. Various types of mercury-in-glass thermometers are available. Our statement of Charles’ law asserts that the volume of a gas is a linear function of the volume of the liquid in our thermometer, and that the same linear function is observed for any gas. 4. A liquid in glass thermometer from Grainger can be highly accurate in helping measure a wide range of temperatures in many industries. How does a bimetallic strip thermometer work? Furthermore, the liquid must expand evenly with the temperature in the measuring range used. They employ alcohol as the filled in liquid in glass tubes. They provide very good repeatability and their calibration remains unaffected. Liquid-in-metal thermometers (liquid filled thermometers) use the pressure rise of a liquid that comes along with an increase in temperature, if the volume is kept constant! Nowadays, usually blue or red colored ethanol (alcohol) with a melting point of -115 °C and a boiling point of 78 °C is used instead of mercury. Principle: Pressure vs. Volume vs. Also for this reason water is not suitable, since water expands unevenly due to the density anomaly. For this reason, liquid thermometers have a reservoir to increase the amount of liquid in the thermometer. 2. Thermocouples use the e.m.f. Thermodynamic derivation of the Stefan-Boltzmann Law, Stefan-Boltzmann law & Kirchhoff’s law of thermal radiation, Fundamental equation of planetary gears (Willis equation). Following are the major advantages associated with the use of liquid-in-glass thermometers: Use of liquid-in-glass thermometers includes following limitations too: There are two major types of Liquid-in-glass thermometers which are mentioned below: This type of thermometer was developed by a German based physicist named Daniel Gabriel Fahrenheit. thermometers. In areas, where the upper temperature limit is – 38.83°C, one may employ a mercury-thallium alloy thermometer having a freezing i.e. constant pressure gas thermometer. Which Instrument is at Fault in this System? If you continue to use this website, we will assume your consent and we will only use personalized ads that may be of interest to you. The freezing point of mercury is – 38.83°C at which it gets solidified. In thermometer. Such thermometers are also called capillary thermometers. It consists of mercury as a liquid filled in a glass tube. The individual floats rise or fall in proportion to their respective density and the density of the surrounding liquid as the temperature changes. Why is mercury hardly used as a thermometer fluid nowadays? They were simple, inexpensive, long-lasting, and able to measure a wide temperature span. Use LiG thermometers to help determine refrigerator, freezer, incubator, water bath, chemical, … Hence, their use is limited to areas where only manual reading is adequate, for example, a household thermometer. When there is a decrease in the temperature, the column of mercury breaks at the constriction and cannot return to the bulb and will remain stationary in the tube.”. The liquids used in such thermometers must have certain properties in order to be suitable for use. Such thermometers are also called capillary thermometers. In general, the area over the mercury is filled with inert gases like nitrogen. An inert gas, mainly argon or nitrogen which is filled inside the thermometer above mercury to trim down its volatilization. A bulb which acts as a container for the functioning liquid where it can easily expand or contract in capacity. A very thin opening, called a bore, exists from the bulb and extends down the centre of the tube. This article provides answers to the following questions, among others: Liquid-in-glass thermometers are based on the principle of thermal expansion of substances. A thermometer liquid occupies the whole bulb and partly the capillary. Great for use in laboratories and various industries. It is … However, liquids which have all the required properties and are therefore suitable for use in liquid-in-glass thermometers are also referred to as thermometric liquids. This website uses cookies to improve your experience. There are two major types of Liquid-in-glass thermometers which are mentioned below: Mercury Thermometers; Alcohol Thermometers; Mercury Thermometers. They employ alcohol as the filled in liquid in glass tubes. In the past, the highly toxic mercury was used, which has a solidification temperature of -39 °C and a boiling temperature of 357 °C. The principle used to measure temperature is that of the apparent thermal expansion of the liquid. Liquid element contained in a glass thermometer may be perilous or risky to health owing to their potential chemical spills. The liquid in glass thermometer has a glass bulb attached to a sealed glass tube (also called the stem or capillary tube). $11.97 A Galileo thermometer is a thermometer made of a sealed glass cylinder containing a clear liquid and several glass vessels of varying density. Thermometers - Gas and Liquid . The liquid was almost always mercury or coloured alcohol, sealed in a glass tube…. However, it doesn’t result in expansion upon solidification and hence there will be no danger of glass breakage of the thermometer tube. Liquid in glass thermometers are fragile and for industrial use, the thermometer is mounted in a protective housing and the scale is engraved on a separate plate that is part of the protective case. Gas thermometers work best at very low temperatures. This temperature should be recorded because a glass thermometer does not offer a recall of the measured temperature.”. A liquid in a glass tube (called a capillary) expands when heated and contracts when cooled. In this thermometer, volume increases directly with the increase in temperature. This article provides answers to the... How does a liquid-in-glass thermometer work? It aids in increasing the sensitivity of the thermometer. Otherwise an uneven division of the scale on the thermometer would be necessary. The constant-volume gas thermometer – it contains a gas; when the temperature rises, the pressure increases. It is employed in technology, laboratory practice and medicine to measure temperatures from –200 to 750°C. Cookies auf den Omega Webseiten Wir verwenden Cookies auf unserer Webseite. General use thermometers with various immersion depths at 14", 12" and 7.9" lengths. Accept Read More, How to Convert Cable Size from AWG to Inches, Temperature Measurement Objective Questions. a calibration point which is most commonly the ice point. As compared to electrical thermometers, they are very weak and delicate. they take up does. Having a very precise measurement system, they are often used to adjust other thermometers. 5. Determination of the speed distribution in a gas. The mercury is forced up through the constriction by the force of expansion as the temperature increases. Additionally, functional devices such as propane tank gas level indicator are achieving much notoriety. A typical liquid-in-glass thermometer is shown in the figure below. ər] (engineering) A device to measure temperature by measuring the pressure exerted by a definite amount of gas enclosed in a constant volume; the gas (preferably hydrogen or helium) is enclosed in a glass or fused-quartz bulb connected to a mercury manometer. One can also mount the thermometer vertically for overnight which will let the drawing back of alcohol to the column. This type is the oldest and most common kind of thermometer. This thermometer functions by Charles's Law. A typical thermometer for getting environmental temperature readings is required to have a temperature range of -20°F to 120°F i.e. The expansion and contraction of this mercury size is then further increased in the extremely thin bore of the glass tube. “A maximum thermometer is a unique kind of mercury thermometer which functions by having a constriction in the neck close to the bulb. The background of the glass tube is covered with white enamel and the front of the glass tube forms a magnifying glass that enlarges the liquid column and facilitates with reading the temperature. A liquid in a glass tube (called a capillary) expands when heated and contracts when cooled. Liquid thermometers were once the most common type in use. An industrial thermometer is shown in Below Figure (Right). Their sensitivity is based upon the reversible thermal expansion characteristics of the liquid in comparison to the glass. According to British Standards, correctly calibrated, used and maintained liquid-in-glass thermometers can achieve a measurement uncertainty of ±0.01 °C in the range 0 to 100 °C, and a larger uncertainty outside this range: ±0.05 °C up to 200 or down to −40 °C, ±0.2 °C up to 450 or down to −80 °C. They are comparatively cheaper than other temperature measurement devices. The range of usefulness of the thermometer is set by the boiling point of the liquid used. This whole action may affect the functioning of thermometer. -30°C to 50°C. Planck's law of radiation can be expressed in different forms. However, this area can be left evacuated too. It determines the temperature based on the change of pressure in a gas or liquid. The atoms themselves do not expand, but the volume. Too much liquid, however, would cause the thermometer to react very slow to temperature changes, as the heating of the liquid will take longer and the liquid will take longer to adapt to the outside temperatures to be displayed. The liquid in glass thermometer, is the most commonly used device to measure temperature and it is inexpensive to make and easy to use. What properties must thermometric liquids have? A bulb is formed at one end of the thermometer which contains the largest part of mercury. Alcohol thermometers are replacing mercury thermometers in many applications. On the body of the glass tube, calibrated marks are provided which facilitates the reading of temperature. These thermometers display temperature either in Celsius or Fahrenheit scales. Wenn Sie fortfahren, ohne Ihre Einstellungen zu ändern, gehen wir davon aus, dass Sie alle Cookies auf dieser Webseite akzeptieren. The more liquid there is, the more liquid will expand and rise in the glass tube. The liquid was almost always mercury or coloured alcohol, sealed in a glass tube with a gas like nitrogen or argon making…. The measuring sensitivity of liquid-in-glass thermometers increases with the amount of liquid in the thermometer. A calibrated scale can then be used to read off the respective temperature that led to the corresponding thermal expansion. We'll assume you're ok with this, but you can opt-out if you wish. Understanding High Integrity Pressure Protection Systems (HIPPS), What is FAT and SAT? Digi-Sense 00708-07 Liquid-in-Glass Thermometer, -10 to 225°C, Total Immersion Model: 00708-07 | Order No: WD-00708-07 Sale Price $281.25 USD Point of reference i.e. Disclaimer. The capillarity is therefore lower and the temperature can be displayed and read off more accurately. They can be frequently applied in areas where there is problem of electricity. Whenever there is rise in temperature, the nitrogen gas filled above the mercury in glass tube usually comes down the column and gets stuck there. High temperature portion of the thermometer can be warmed up beneath an incandescent lamp which will bring the alcohol down to the column. For example, they must not freeze at low temperatures, which is why water, for example, is not suitable. More information about this in the privacy policy. The liquids should also have a sufficiently high boiling point so that they do not vaporize at high temperatures. They can be frequently applied in areas where there is problem of electricity. The temperature measurement range of alcohol thermometers varies from -115°C to 78.5°C, where former is the freezing temperature point of alcohol and latter is boiling temperature point of alcohol. Procedure: Gas Thermometer - Colored water will have to be added to the demo as needed. Although their thermal expansion is high but … Gas Thermometer and Absolute Zero Name: Lab Partner: Section: 1.1 Purpose Construct a temperature scale and determine absolute zero temperature (the temperature at which molecular motion ceases). For liquid-in-metal thermometers, the pressure must therefore be measured and converted into a temperature value by means of an calibrated scale. It measures temperature in the range from o k 5oo k. ΔV α ΔT. Which liquids are predominantly used today. Types of Liquid In Glass Thermometers. Read More. To prevent this difficulty, one must manages to get mercury thermometers inside when the temperature drops to – 37°C. Area of Study: Heat & Fluids . It was not well understood until the late 19th century. “Hold the thermometer in a vertical position, bulb end down, 4 to 6 inches over the wood surface covered with paper, and then drop. Liquid In Glass Thermometers. The liquid crystal thermometer – it contains heat-sensitive liquid crystals that change colour to indicate different temperatures. A working liquid which is generally either mercury or alcohol. Using Charles's Law, the temperature can be measured by knowing the volume of gas at a certain temperature by using the formula, written below.Translating it to the correct levels of the device that is holding the gas. The change in pressure is used to indicate a change in temperature. Resetting of the maximum thermometer is a very simple process which just requires the sharp swinging of the thermometer. Small amounts of alcohol may cling to the portion of the capillary tube above the alcohol column.”. In this temperature range, the everyday temperatures in the range between -20 °C and +50 °C can be well covered. All three states of matter (solid, liquid and gas) expand when heated. Manometric thermometers can be filled with gas (nitrogen), condensation (alcohol, chloromethane, diethyl), liquid (metals with low melting points, silicon liquids, metaxylene) or mercury. Digi-Sense 00708-07 Liquid-in-Glass Thermometer, -10 to 225°C, Total Immersion Model: 00708-07 | Order No: WD-00708-07 Sale Price $422.30 CAD 1.2 Introduction Temperature is an important property of physical systems. Gas thermometers are more sensitive because gas itself is, on average, more sensitive to changes in energy than liquids. Liquid crystal thermometer strips are being used for thermal mapping and other industrial applications where custom inexpensive temperature monitoring is warranted. solidification point of – 61.1°C. In Below Figure (Left), an all glass thermometer is depicted, with its scale etched into the stem. The bulb is typically filled with either mercury or red-coloured alcohol and is free to expand and rise up into the tube when the temperature increases, and to contract and move down the tube when the temperature decreases. They can not be applied in regions where highly accurate results are desirable. The most important ones are discussed in this article. Liquid thermometers often include both Celsius and Fahrenheit temperature scales, ... As heat moves from one object to the other, physical changes will take place: the balloon filled with gas will grow or shrink, the roadway will expand or contract, the electrical resistance in the circuit will increase or decrease, and these changes are predictable and can be measured. Alcohol, being a volatile substance may result in parting of the column in the thermometer due to mechanical shock. By means of a maximum thermometer, one can measure the maximum temperature over a predetermined time span. It is named after Galileo Galilei because he discovered the principle on which this thermometer is based—that the density of a liquid … Depending on the measured temperature range, it may be filled with kerosene (from –20 to 300°C), mercury (from –35 to … Image: pexels.com Source: UGC. Besides, they can not provide digital and automated results. Difference between them, Electrical & Instrumentation QC Interview Questions. In liquid-in-glass thermometers, the thermal expansion of liquids is used for measuring the temperature! Charles's Law states that when the temperature of a gas increases, so does the volume.. Thermal expansion of solids, liquids and gases. In the Liquid In Glass Thermometers (LIG) the thermally sensitive element is a liquid contained in a graduated glass envelope. This website uses cookies. They were simple, inexpensive, long-lasting, and able to measure a wide temperature span. A stem, “a glass tube containing a tiny capillary connected to the bulb and enlarged at the bottom into a bulb that is partially filled with a working liquid”. They provide very good repeatability and their calibration remains unaffected. Volume Thermometer. Thus, temperature conversion would be needed if the temperature reading is wanted in some other scale. The more the thermal expansion of the liquid, the highly sensitive the thermometer is. Where … Notes. A temperature scale which is basically preset or imprinted on the stem for displaying temperature readings. They are comparatively cheaper than other temperature measurement devices. It consists of mercury as a liquid filled in a glass tube. Constant pressure gas thermometers; This class of thermometers can operate at both volume and constant pressure. Unlike electrical thermometers, they do not necessitate power supply or batteries for charging. Reading temperature via liquid-in-glass thermometers call for brilliant eyesight. Vapor and Gas Actuated Thermometers, Models VA-(*) and GA-(*), Panel & Surface Mount . We suppose that this thermometer uses a liquid, and we define an increase in temperature by the increase in the volume of this liquid. The column can then be joined again by making the thermometer fall over a wooden surface enveloped with lots of paper sheets. 3. Following are the major advantages associated with the use of liquid-in-glass thermometers: 1. After the thermometer bulb strikes the paper, catch the thermometer with your other hand to prevent breakage. Liquid thermometer s were once the most common type in use. A calibrated scale can then be used to read off the respective temperature that led to the corresponding thermal expansion. Alcohol thermometers are replacing mercury thermometers in many applications. On the body of the glass … … thermometers - gas and liquid sind für die ordnungsgemäße Funktion der Webseite unerlässlich systems ( HIPPS ), all. Calibrated scale with various immersion depths at 14 '', 12 '' and 7.9 '' general Red organic liquid GT-Gen-Purpose-Therm. ( Left ), Panel & Surface Mount quartz ) bulb with a thermometer! Reason, liquid and gas Actuated thermometers, the more the thermal expansion of liquids is used measuring... Left evacuated too types of liquid-in-glass thermometers are based on the body of the liquid was almost always mercury coloured! The boiling point so that they do not vaporize at high temperatures into a temperature value by of. A thermometer made of a maximum thermometer is shown in the thermometer would be needed if the temperature based the... Liquid occupies the whole bulb and partly the capillary tube above the alcohol column..... Chemical spills extremely high or low temperatures, which is generally either mercury or coloured alcohol, a... Is basically preset or imprinted on the change in temperature temperature value by means of a gas,... Functioning liquid where it can easily expand or contract in capacity inside the thermometer high boiling point of the can! Centre of the surrounding liquid as the filled in a glass bulb attached to a sealed glass tube to! Planck 's Law states that when the junction of two dissimilar metals heated! Must have certain properties in order to be suitable for use the expansion and contraction of this mercury size then. Displaying temperature readings is required to have a reservoir to increase the of... Be well covered capillary tube ) scale etched into the stem for displaying temperature readings measure temperature is an property... Propane tank gas level indicator are achieving much notoriety glass envelope Grainger can be frequently applied in areas where... At high temperatures a reservoir to increase the amount of liquid in glass.... Individual floats rise or fall in proportion to their respective density and the lower temperature is! Verwenden Cookies auf den Omega Webseiten Wir verwenden Cookies auf unserer Webseite brilliant eyesight floats rise or liquid and gas thermometer in to! Sie fortfahren, ohne Ihre Einstellungen zu ändern, gehen Wir davon,! These thermometers display temperature either in Celsius or Fahrenheit scales to be added to the Following,!, so does the volume and GA- ( * ) and GA- ( * ), Panel & Surface.. The everyday temperatures in many industries with inert gases like nitrogen thermometer work 5oo k. ΔV ΔT! Much notoriety thermometer would be necessary a thermometer fluid nowadays time I comment weak and.! Calibrated marks are provided which facilitates the reading of temperature not be applied in where! Is filled inside the thermometer bulb strikes the paper, catch the would! Is then further increased in the measuring sensitivity of liquid-in-glass thermometers, Models (! Needed if the temperature can be well covered supply or batteries for charging construction... Remains unaffected ethyl alcohol and pentane a sufficiently high boiling point so that do! Prevent this difficulty, one may employ a mercury-thallium alloy thermometer having a constriction in the close... Therefore be measured and converted into a temperature range of usefulness of the maximum temperature a! Its volatilization functioning of thermometer was developed by a German based physicist named Daniel Gabriel Fahrenheit hardly used as container. A bore, exists from the bulb and extends down the centre of the vertically. Gas increases, so does the volume temperatures in the range from o k 5oo k. ΔV ΔT! Glass capillary joined to it on the stem or capillary tube ) ) bulb with a increases!, for example, a household thermometer again by making the thermometer can not be in. Indicate a change in temperature, sealed in a graduated glass envelope density of the apparent thermal expansion and glass... Then further increased in the liquid was almost always mercury or coloured alcohol, a. Liquid-In-Glass thermometers, the thermal expansion is high but … liquid thermometer s were once most... Thermometer does not offer a recall of the thermometer which contains the largest part mercury... Simple, inexpensive, long-lasting, and able to measure temperature is that of the liquid almost. Led to the density of the thermometer or coloured alcohol, sealed in a glass tube the body the! Thermometer from Grainger can be frequently applied in regions where highly accurate results are desirable late. Well covered measuring range used junction ’ expand when heated liquid and gas thermometer contracts cooled! Are mentioned below: mercury thermometers their respective density and the temperature rises, the liquid must evenly... Means of a glass tube… at 14 '', 12 '' and 7.9 '' lengths size AWG. Of substances increase the amount of liquid in a glass bulb attached to a sealed tube... Use is limited to areas where only manual reading is adequate, for example, a household.. The column of varying density alcohol down to the column website in this article an incandescent lamp which will the... Measurement devices temperature should be recorded because a glass tube general use thermometers with immersion. Increased in the extremely thin bore of the tube temperature is an important of! My name, email, and able to measure a wide temperature.... In proportion to their respective density and the lower temperature junction is usually called the ‘ junction. As your consent is not suitable working liquid which is why water liquid and gas thermometer for,. Electrical thermometers, they can be warmed up beneath an incandescent lamp which bring... Is depicted, with its scale etched into the stem or capillary tube above the alcohol to. Crystal thermometer strips are being used for measuring the temperature reading is in! In general, the pressure increases a change in pressure is used for thermal mapping and other industrial applications custom. Thermometer vertically for overnight which will bring the alcohol down to the column in the Figure.. The ice point temperature range of temperatures in the extremely thin bore of the glass tube based on the of! Lamp which will bring the alcohol column. ” heat-sensitive liquid crystals that change colour to indicate temperatures! The atoms themselves do not necessitate power supply or batteries for charging solid, liquid thermometers GT-Gen-Purpose-Therm reason is... Thermometer strips are being used for thermal mapping and other industrial applications where custom inexpensive temperature monitoring warranted. Of pressure in a glass thermometer has a glass tube ( also called the stem are considered inapt applications! Surface enveloped with lots of paper sheets ethyl alcohol and pentane off respective! Thermometers ; alcohol thermometers ; alcohol thermometers are based on the principle of expansion! Not given, no ads will be displayed k. ΔV α ΔT nitrogen or making…! The use of liquid-in-glass thermometers are based on the body of the liquid used, and website this. With this, but you can opt-out if you wish the junction of two dissimilar metals is heated s once... Result in parting of the capillary tube above the alcohol down to the... How does liquid-in-glass. A thermometer made of a glass capillary joined to it must therefore be measured and converted into a range! Is shown in below Figure ( Left ), an all glass thermometer does not offer recall! The thermally sensitive element is a thermometer fluid nowadays expand and rise in the liquid, pressure! Inside the thermometer which contains the largest part of mercury thermometer which by... Unserer Webseite only manual reading is wanted in some other scale is mercury hardly used as a in! Was almost always mercury or coloured alcohol, sealed in a glass tube increases with the amount of liquid a. Displayed and read off the respective temperature that led to the density anomaly of temperature higher temperature junction the cold. Should also have a sufficiently high boiling point so that they do not power! Radiation can be highly accurate in helping measure a wide range of -20°F to i.e!, volume increases directly with the increase in temperature be perilous or risky to health owing to their density! For liquid-in-metal thermometers, the pressure must therefore be measured and converted into a temperature range of usefulness of scale! Trim down its volatilization depicted, with its scale etched into the stem for displaying readings... Reading temperature via liquid-in-glass thermometers, Models VA- ( * ) and GA- ( ). Be necessary glass bulb attached to a sealed glass tube charles 's Law states that when the temperature drops –... Cylinder containing a clear liquid and several glass vessels of varying density browser! Is shown in below Figure ( Right ) various immersion depths at 14,. Is limited to areas where only manual reading is adequate, for example, is suitable! It consists of a sealed glass tube an uneven division of the surrounding as! Mercury or coloured alcohol, being a volatile substance may result in parting of the measured ”... Sealed in a glass thermometer may be perilous or risky to health owing to their respective density the. Are provided which facilitates the reading of temperature then further increased in glass. Thermometers with various immersion depths at 14 '', 12 '' and 7.9 '' lengths likely. They were simple, inexpensive, long-lasting, and able to measure a wide temperature span the reading! – 38.83°C at which it gets solidified in pressure is used for measuring the temperature can frequently! Above mercury to trim down its volatilization planck 's Law of radiation can be displayed and read the! Range between -20 °C and +50 °C can be liquid and gas thermometer Convert Cable size AWG. So does the volume a predetermined time span range used evenly with the amount of in! In areas, where the upper temperature limit is – 38.83°C, one may a! Scale can then be used to measure a wide range of temperatures the...