Cloud feedbackCloud feedback is the coupling between cloudiness and surface air temperature where a surface air temperature change leads to a change in clouds, which could then amplify or diminish the initial temperature perturbation. Cloud feedbacks can affect the magnitude of internally generated climate variability or they can affect the magnitude of climate change resulting from external radiative forcings. Global warming is expected to change the distribution and type of clouds.
Characteristic function (probability theory)In probability theory and statistics, the characteristic function of any real-valued random variable completely defines its probability distribution. If a random variable admits a probability density function, then the characteristic function is the Fourier transform of the probability density function. Thus it provides an alternative route to analytical results compared with working directly with probability density functions or cumulative distribution functions.
Precipitation typesIn meteorology, the different types of precipitation often include the character, formation, or phase of the precipitation which is falling to ground level. There are three distinct ways that precipitation can occur. Convective precipitation is generally more intense, and of shorter duration, than stratiform precipitation. Orographic precipitation occurs when moist air is forced upwards over rising terrain and condenses on the slope, such as a mountain.
Central limit theoremIn probability theory, the central limit theorem (CLT) establishes that, in many situations, for independent and identically distributed random variables, the sampling distribution of the standardized sample mean tends towards the standard normal distribution even if the original variables themselves are not normally distributed. The theorem is a key concept in probability theory because it implies that probabilistic and statistical methods that work for normal distributions can be applicable to many problems involving other types of distributions.
BioaerosolBioaerosols (short for biological aerosols) are a subcategory of particles released from terrestrial and marine ecosystems into the atmosphere. They consist of both living and non-living components, such as fungi, pollen, bacteria and viruses. Common sources of bioaerosols include soil, water, and sewage. Bioaerosols are typically introduced into the air via wind turbulence over a surface. Once in the atmosphere, they can be transported locally or globally: common wind patterns/strengths are responsible for local dispersal, while tropical storms and dust plumes can move bioaerosols between continents.
Coefficient of variationIn probability theory and statistics, the coefficient of variation (COV), also known as Normalized Root-Mean-Square Deviation (NRMSD), Percent RMS, and relative standard deviation (RSD), is a standardized measure of dispersion of a probability distribution or frequency distribution. It is defined as the ratio of the standard deviation to the mean (or its absolute value, , and often expressed as a percentage ("%RSD"). The CV or RSD is widely used in analytical chemistry to express the precision and repeatability of an assay.
Airborne transmissionAirborne transmission or aerosol transmission is transmission of an infectious disease through small particles suspended in the air. Infectious diseases capable of airborne transmission include many of considerable importance both in human and veterinary medicine. The relevant infectious agent may be viruses, bacteria, or fungi, and they may be spread through breathing, talking, coughing, sneezing, raising of dust, spraying of liquids, flushing toilets, or any activities which generate aerosol particles or droplets.
Aerosol spray dispenserAerosol spray is a type of dispensing system which creates an aerosol mist of liquid particles. It comprises a can or bottle that contains a payload, and a propellant under pressure. When the container's valve is opened, the payload is forced out of a small opening and emerges as an aerosol or mist. The concepts of aerosol probably go as far back as 1790. The first aerosol spray can patent was granted in Oslo in 1927 to Erik Rotheim, a Norwegian chemical engineer, and a United States patent was granted for the invention in 1931.
NucleationIn thermodynamics, nucleation is the first step in the formation of either a new thermodynamic phase or structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organized structure appears. For example, if a volume of water is cooled (at atmospheric pressure) below 0 °C, it will tend to freeze into ice, but volumes of water cooled only a few degrees below 0 °C often stay completely free of ice for long periods (supercooling).
Political campaignA political campaign is an organized effort which seeks to influence the decision making progress within a specific group. In democracies, political campaigns often refer to electoral campaigns, by which representatives are chosen or referendums are decided. In modern politics, the most high-profile political campaigns are focused on general elections and candidates for head of state or head of government, often a president or prime minister. The message of the campaign contains the ideas that the candidate wants to share with the voters.
