比尔-兰伯特定律

地磁长期变化是指地球磁场在数年到数千年时间尺度上的缓慢变化。这些变化包括磁场强度和偶极轴方向的偏移，以及非偶极特征的西移。这种变化是由地核外层熔融铁的流动变化引起的，而熔融铁正是地磁发电机的源头。

Relative humidity ([latex]\phi[/latex]) is the ratio of the partial pressure of water vapor ([latex]p_{H_2O}[/latex]) to the equilibrium vapor pressure of water ([latex]p^*_{H_2O}[/latex]) at a given temperature. It is expressed as a percentage: [latex]\phi = \frac{p_{H_2O}}{p^*_{H_2O}} \times 100\%[/latex]. It indicates how close the air is to saturation, where 100% RH means the air is saturated.

The Air Mass (AM) coefficient quantifies the direct optical path length of sunlight through Earth's atmosphere. It is the ratio of the path length at a given zenith angle [latex]\theta[/latex] to the path length when the sun is directly overhead (at the zenith). For angles up to about 60°, it can be approximated by [latex]AM \approx \sec(\theta)[/latex]. AM0 refers to the spectrum outside the atmosphere.

生化需氧量 (BOD) 是衡量需氧微生物在分解水中有机物时消耗的溶解氧的指标。标准测试方法 BOD5 是在 20°C 的黑暗环境中密封培养水样五天后测定氧气消耗量。选择五天作为标准测试时间是出于监管方面的实际考虑，同时也是为了模拟典型的河流航行时间。

地球磁场是由地磁发电机机制产生的。外核中导电熔融铁的对流，在地球自转产生的科里奥利力的影响下，形成了一个自持的电流系统。这些电流产生了地球的大尺度磁场，其作用类似于一个巨大的电磁铁。这一过程可以用磁流体动力学（MHD）来描述。

总生化需氧量 (BOD) 由两大过程组成：碳源生化需氧量 (cBOD) 和氮源生化需氧量 (nBOD)。cBOD 是微生物氧化有机碳化合物所消耗的氧气。nBOD 是特定自养细菌在后期氧化含氮化合物（主要是氨，即硝化作用）过程中消耗的氧气。区分 cBOD 和 nBOD 对于高级废水处理至关重要。

Photochemical smog is formed through a complex series of reactions involving sunlight, nitrogen oxides (NOx), and volatile organic compounds (VOCs). The process is initiated when sunlight splits nitrogen dioxide ([latex]NO_2[/latex]) into nitric oxide (NO) and an oxygen atom (O). This free oxygen atom then combines with molecular oxygen ([latex]O_2[/latex]) to form ground-level ozone ([latex]O_3[/latex]), a primary component of smog.

露点是指在恒定压力和水含量下，空气冷却至饱和状态所需的温度。在此温度下，相对湿度为100%。如果空气进一步冷却，水蒸气会凝结成液态水（露水），如果温度低于冰点，则会结霜。

The solar constant is the mean solar electromagnetic radiation per unit area measured at the top of Earth's atmosphere, perpendicular to the rays. Its value is approximately 1361 watts per square meter ([latex]W/m^2[/latex]). This figure varies slightly with solar activity and Earth's orbital distance, but serves as a fundamental baseline for climate science, satellite design, and renewable energy calculations.

Acid rain results from atmospheric sulfur dioxide (SO2) and nitrogen oxides (NOx) reacting with water, oxygen, and other chemicals. SO2 is oxidized to sulfuric acid ([latex]H_2SO_4[/latex]), and NOx forms nitric acid ([latex]HNO_3[/latex]). These reactions, often catalyzed by sunlight, produce highly acidic compounds that fall to Earth as wet or dry deposition, harming ecosystems.

地球平流层臭氧层对生命至关重要，因为它吸收了太阳中相当一部分有害的紫外线辐射。它完全阻挡了能量最高的UVC射线，吸收了约95%的UVB射线，并允许大部分危害较小的UVA射线穿过。这种过滤作用保护了陆地生物免受严重的DNA损伤。

荧光增白剂，也称为光学增白剂 (OBA)，是一种能够增强白色感的化合物。它们吸收人眼不可见的紫外 (UV) 光谱中的光，并将其重新发射为可见光谱中蓝色区域的光。这种蓝光可以中和材料中残留的黄色或乳白色光泽。

核磁共振 (NMR) 波谱技术是一种利用特定原子核磁性的技术。它将样品置于强而恒定的磁场中，并用无线电波进行探测。原子核吸收并以特定的共振频率重新发射电磁辐射，该频率取决于分子内磁场，从而揭示有关分子结构、动力学和化学环境的详细信息。