Temperature, dew point (a measure of humidity), wind speed, wind direction, current weather, barometric pressure and pressure tendency (is it increasing or falling? ), cloud cover, and many other factors are frequently included. The choice of symbols to depict these factors is very important, as they tell us much about the nature of the weather involved.
There are several different systems in use today for indicating weather conditions on weather maps. Each system has its advantages and disadvantages; which one is best depends on what you want to show people.
Humidity, air temperature and pressure, wind speed and direction, cloud cover and type, and precipitation volume and shape are all atmospheric aspects of what we name "weather." Weather conditions can change rapidly, so it is important for us to be aware of what these changes mean for our safety. The physical properties of clouds determine how they will affect our weather, so let's take a look at those.
Clouds are collections of liquid or solid particles that are suspended in a gas. There are three main types of clouds: cirrus, cumulus, and stratus. Each type has different effects on weather patterns.
Cirrus clouds are high in the atmosphere and look like wispy strands or curtains reaching for the sky. They usually contain more ice crystals than other clouds and can appear blue, gray, or white depending on their height above the earth.
Cumulus clouds are low to mid-level clouds that look like puffy balls or tufts of cotton hanging in the air. They often contain many small droplets of water inside which cause them to reflect light from the sun back into the atmosphere where it can be caught by warmer air molecules and fallen as rain or snow. Cumulus clouds can be white, grey, or dark blue depending on their height above the earth.
A standard plotting code indicates wind direction and speed, air temperature and dew point, barometric pressure and its change over the preceding hours, the amount and types of clouds, the weather type, including visibility restrictions, and the amount and type of precipitation at many locations on the map. The data are obtained from government agencies and private sources.
The U.S. National Weather Service publishes daily maps that show which portions of the country are covered by precipitation sensors (rain gauges for short). These so-called Rainfall Maps display the average annual total rainfall at each sensor location. They are updated daily if necessary.
Maps showing the maximum and minimum temperatures during the day come from thermal imaging cameras mounted on aircraft or satellites. These instruments capture images of Earth's surface temperature every few minutes, so they provide a comprehensive picture of climate across large regions full of varying landscapes and human activities. The maps show how heat is distributed across the planet, providing information about the underlying physics of climate change.
Maps showing storm tracks and other severe weather patterns are useful tools for predicting where storms may be dangerous and who might be at risk. Scientists use the term "severe weather" to describe any natural disaster caused by wind, rain, snow, ice or volcanic activity. This includes hurricanes, typhoons, cyclones and tornados but also floods, droughts and heat waves.
Station-model maps depict the weather conditions at a specific weather station. They provide information on a variety of meteorological variables, including temperature, humidity, air pressure, cloud cover, and wind speed. Station-model maps are created by collecting data from many different stations across the country or world. These observations are then plotted on a map using an algorithm known as gridding.
Surface-model maps show weather conditions over large areas. They often include graphs depicting various quantities such as surface temperatures, atmospheric pressures, or moisture levels. Surface-model maps are generated by sending sensors into the field to collect data on physical properties such as temperature and humidity. This information is then used to create models of the atmosphere over large regions.
Mesoscale models divide the Earth's surface into smaller regions called meso-cells. Each cell can have its own set of environmental conditions based on local factors such as topography, land use, and ocean currents. Mesoscale models calculate these conditions by applying physics-based algorithms to data collected by instruments mounted on aircraft or satellites.
Microscale models describe small regions within larger geographical locations such as buildings, streets, or counties. Microscopic models derive their name because they display details down to the scale of 1/100,000th of a mile (1 kilometer).
The weather in the area is caused by external forces. There are four of them: heat energy, air pressure, wind, and moisture. Weather data from the Earth's surface and atmosphere must be collected in order to create weather maps or forecast weather. Weather maps and data are analyzed by scientists in order to forecast the weather. Forecasters use this information when creating forecasts for their audiences.
External forces cause changes to the density of the atmosphere above any given point on the surface. These changes in density cause effects called "weather phenomena," such as clouds and rain drops. Detecting these phenomena and recording their occurrences over time allows meteorologists to build up a picture of how the atmosphere works. This information can then be used to predict future weather events.
Meteorologists use several methods to collect data on external forces causing weather phenomena. They may use self-reporting tools like questionnaires or open text fields in order to obtain detailed information from people who experience certain weather phenomena. They may also use observational tools like digital cameras or specialized instruments that measure specific aspects of the environment such as humidity or temperature sensors. Observational tools provide the most comprehensive record of what happens with respect to weather phenomena but are limited to those places where they are able to install the equipment required.
Scientists work with small samples of the total environment in order to reduce uncertainty about the nature of conditions elsewhere.