Thermometer is an instrument for measuring temperature consisting typically of a glass bulb attached to a fine tube of glass with a numbered scale and containing a liquid that is sealed in and rises and falls with changes of temperature. A barometer on the other hand is used to measure atmospheric pressure. A typical barometer employs a mercury-filled glass tube, sealed at one end with a mercury reservoir at the other end. The mercury then adjusts between the tube and the reservoir to reflect atmospheric pressure. Low pressure will cause the mercury to drop in the tube.
High pressure forces the mercury to rise in the column.
The process by which water vapor changes into water droplets and clouds is known as Condensation, while saturation means the maximum amount of water vapor a mass of air can hold at its current temperature. Usually found in the stratosphere, a colorless gas and a form of oxygen which is responsible for filtering out much of the sun's ultraviolet radiation and thus restricting them to enter the earth's atmosphere. Greenhouse effect is the progressive, gradual warming of the earth's atmospheric temperature, caused by the insulating effect of carbon dioxide and other greenhouse gases that have proportionately increased in the atmosphere. The main culprits to the greenhouse effect are greenhouse gases. Increase in concentrations of the latter four gases have been linked to emissions from human activity.