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GROUP MEMBERS Sutiana Allen Claudine Beckford Mitchell Yannike blackwood. What is Weather ?.
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Claudine Beckford Mitchell
Weather is the day-to-day state of the atmosphere, and its short-term variation in minutes to weeks. People generally think of weather as the combination of temperature, humidity, precipitation, cloudiness, visibility, and wind. We talk about changes in weather in terms of the near future: "How hot is it right now?" "What will it be like today?" and "Will we get a snowstorm this week?"
Climate is the weather of a place averaged over a period of time, often 30 years. Climate information includes the statistical weather information that tells us about the normal weather, as well as the range of weather extremes for a location.
The clear difference between weather and climate is the time period.
Weather is seen on a day to day basis and climate is the average weather conditions over a period of years.
Air pressure basically refers to the volume of air in a particular environment, with greater volumes creating higher pressures. On the earth's surface, for example, it is known as "atmospheric pressure" and refers to the weight of the earth's atmosphere pressing down on everything. Changes in pressure can impact the temperature, weather patterns, and cause physiological problems for people and animals. This pressure can even impact the performance of a basketball or similarly inflated object.
On the earth, the average air pressure at sea level is 1.03 kilograms per square centimeter (kg/cm2) or 14.7 pounds per square inch (psi); this is commonly measured in bars, in which atmospheric pressure is about 1 bar. This means that hundreds of pounds of pressure are pressing on everyone from all sides, at all times. Humans and other animals are able to survive this pressure because their bodies evolved on the surface where it is natural. If the pressure increases or decreases, it can result in discomfort or even death.
Atmospheric pressure varies slightly over the earth's surface, and variations in pressure are responsible for various types of weather. Low pressure systems are associated with storms, tornadoes, and hurricanes. Sometimes the air pressure at sea level can drop as low as 870 millibars, which is about 85% of average air pressure. This only happens during the most severe storms. Pressure variations on the earth's surface cause wind: as high pressure air moves toward low pressure areas, creating gusts.
Relative humidity is a measure of the amount of moisture in the air relative to the total amount of moisture the air can hold. For instance, if the relative humidity was 50%, then the air is only half saturated with moisture. Warmer air can hold more moisture than colder air.
Without humidity, there would be no clouds, no precipitation, and no fog. Humidity is simply water vapor in the air, which is needed to form rain. Additionally, water vapor holds heat in the air. It is a greenhouse gas, which means it is a can absorbs heat and warms the atmosphere. This is why humid air feels warmer.
How is relative humidity measured?
Relative humidity is reported as a percentage of the total amount of moisture that could be held in the air. For instance, if the air is only half saturated with water vapor, the relative humidity will be reported at 50%. If the air holds all the water vapor it can hold, it is 100% saturated.
Hygrometers are instruments used for measuring humidity. A simple form of a hygrometer is specifically known as a "psychrometer" and consists of two thermometers, one of which includes a dry bulb and the other of which includes a bulb that is kept wet to measure wet-bulb temperature.