Video Experimental Relacionado
Updated: Jul 12, 2026

06:27
Measurement of Aerosols Optical Thickness of the Atmosphere using the GLOBE Handheld Sun Photometer
Published on: May 29, 2019
Una intercomparación de las mediciones de la OH troposférica en el Observatorio Fritz Peak, Colorado
Resumen
Las mediciones de las concentraciones de radicales hidroxilo (OH) en la atmósfera muestran acuerdo entre dos métodos. Sin embargo, los niveles de OH observados fueron más bajos de lo predicho por los modelos, lo que sugiere una química atmosférica desconocida.
Área de la Ciencia:
- Química de la atmósfera La química de la atmósfera
- Ciencias ambientales Ciencias ambientales.
- La cinética química es la cinética química.
Sus antecedentes:
- El radical hidroxilo (OH) es una especie clave que controla las vidas atmosféricas de los gases de efecto invernadero y las sustancias que agotan la capa de ozono.
- La medición precisa de las concentraciones de OH es crucial para comprender los procesos atmosféricos y validar los modelos químicos.
Objetivo del estudio:
- Para comparar dos técnicas de medición independientes para las concentraciones de radicales hidroxilo (OH) troposféricos.
- Evaluar la capacidad de los modelos fotoquímicos actuales para predecir las concentraciones de OH.
Principales métodos:
- Se utilizaron dos métodos distintos para la medición de OH: análisis químico y absorción espectroscópica de trayectoria larga.
- Mediciones realizadas en el Pico Fritz bajo diferentes condiciones atmosféricas (contaminadas y limpias).
Principales resultados:
- Acuerdo demostrado entre las dos técnicas independientes de medición de OH.
- Se encontró que las concentraciones de OH medidas eran consistentemente más bajas que las predicciones del modelo fotoquímico.
- Sólo se observó un aumento de dos veces en la concentración de OH desde la madrugada hasta el mediodía en un día despejado.
Conclusiones:
- Las técnicas actuales de medición de OH proporcionan datos fiables para probar modelos fotoquímicos.
- Las discrepancias entre las concentraciones de OH medidas y modeladas sugieren la presencia de carroñeros atmosféricos no identificados.
- Las concentraciones atmosféricas de OH exhiben una variación diurna menor de lo que se esperaba anteriormente.
Videos de Conceptos Relacionados
Flame Photometry: Lab
In a flame photometer, when a solution like potassium chloride is aspirated into the flame, the solvent evaporates, leaving behind dehydrated salt. This salt dissociates into free gaseous atoms in their ground state. Some of these atoms absorb energy from the flame, leading to their excitation. The excited atoms return to the ground state, emitting photons at characteristic wavelengths. Because only electronic transitions are involved, the resulting emission lines are very narrow. The intensity...
Temperature Measurement Sites
A thermometer measures body temperature. The common sites for measuring body temperature are the oral cavity, axillary region, temporal artery, and skin surface, such as the forehead, abdomen, and axilla. True core body temperature is assessed in the rectum, tympanic membrane, pulmonary artery, esophagus, and urinary bladder.
Oral: When assessing oral temperature, the thermometer tip should be placed under the tongue in the posterior sublingual pocket. It offers accurate readings and can be...
Oral: When assessing oral temperature, the thermometer tip should be placed under the tongue in the posterior sublingual pocket. It offers accurate readings and can be...
Precipitation Titration: Endpoint Detection Methods
In argentometric precipitation titrations, endpoints can be detected visually by the Mohr, Volhard, and Fajans methods. In the Mohr method, adding a soluble chromate indicator gives an initial yellow color to the analyte solution. As the titrant is added, the first excess of silver ions forms a red silver chromate precipitate, marking the endpoint. The solution pH should be maintained at about 8 by adding solid CaCO3.
In the Volhard method, a standard excess of AgNO3 is first added to the...
In the Volhard method, a standard excess of AgNO3 is first added to the...
Flame Photometry: Overview
Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...
Variation of Atmospheric Pressure
Change in atmospheric pressure with height is particularly interesting. The decrease in atmospheric pressure with increasing altitude is due to the decreasing gravitational force per unit area as we move away from the surface of the earth.
Assuming the air temperature is constant at a given altitude and that the ideal gas law of thermodynamics describes the atmosphere to a good approximation, one can find the variation of atmospheric pressure with height.
Let p(y) be the atmospheric pressure at...
Assuming the air temperature is constant at a given altitude and that the ideal gas law of thermodynamics describes the atmosphere to a good approximation, one can find the variation of atmospheric pressure with height.
Let p(y) be the atmospheric pressure at...
Attenuated Total Reflectance (ATR) Infrared Spectroscopy: Overview
Attenuated total reflectance (ATR) infrared spectroscopy is a powerful analytical technique used to study the composition of materials. It is widely employed in chemistry, materials science, forensic science, and other fields where sample characterization is required. ATR has several advantages over traditional transmission IR spectroscopy, including the requirement of little to no sample preparation and the ability to analyze a wide range of samples.
The ATR process begins by directing a beam...
The ATR process begins by directing a beam...

