Air

• Thermometers measure air temperature. A thermometer uses a temperature gauge that is marked onto a tube filled usually with alcohol or mercury. The thermometer responds to rises or falls in temperature. By reading the filled tube, we can determine what the actual air temperature is on any given day.
  
  Barometers measure air pressure. It is air pressure changes that most people with weather-sensitive physiologies respond to, although some do respond to relative humidity more so in hot weather. Barometers usually use mercury to assess air pressure; they indicate not only the pressure right now but also if it is rising or falling overall. Whether the pressure is rising or falling indicates the kind of weather to anticipate over the next day or so. Falling barometer readings mean wet, stormy conditions. Rising barometer readings mean you can expect to enjoy sunny, dry weather for a while.
  
  A psychrometer (or sling phsychrometer) uses two thermometers together to determine the level of humidity (moisture) in the air. One of the thermometers has its end wrapped in a wet cloth. The thermometer with the wet cloth has a lower temperature. As the water in the cloth evaporates, the difference in the readings gives a reading that weather professionals (meteorologists) can translate into the amount of relative humidity present in the atmosphere.
  
  A hygrometer is an instrument to determine the actual (versus relative) humidity in the air at a particular time.
  
  

Wind

• Some weather instruments concerned with wind include an anemometer, which is made up of cups attached to a dial. The cups catch the wind, and then the dial records the speed at which the wind was blowing as the cups caught the wind.
  
  A weather vane is a very simple weather instrument that people have used for many years. This instrument shows the direction of wind at the moment. Fundamentally, a weather vane is a metal instrument with a foundation post, and then two cross-pieces atop it; often the crosspieces conclude in a point. Each of the four points of the crosspiece represent one of the primary compass directions: north, east, west and south. As the wind blows, the crosspieces rotate in accordance with wind direction. Weather vanes (or wind vanes) are quite popular with farmers, and often the farmers would add decorative symbols above the functional parts of the vane, such as the animals they raised on their farms: a rooster, pig, horse or cow, for example.
  
  

Rain

• There are many types of rain gauges, and you can make your own at home easily. To make a rain gauge, simply set out a bucket, barrel or large-based but empty planter for growing plants. Leave this bucket out to catch rain. When the rain has collected after your next rainfall, go and measure the amount of rain in your bucket or barrel with a ruler or tape measure. This will tell you what the actual amount of rainfall in inches is for the latest rainfall you have had. While there are different levels of sophistication, all rain gauges work on this principle.
  
  

Upper Atmosphere

• All the elements of weather discussed so far have an impact on intermediate-term weather. So, too, however, do upper atmosphere conditions. Humanity has developed one important instrument to measure upper air weather conditions: the weather balloon. Weather balloons are released into the upper atmosphere to track and record the conditions occurring high above the Earth that have an effect on weather at the level of the Earth's surface.
  
  

Pattern Measurement

• It is important for us to have a sense of what is coming along for weather in the future, as well. This is especially true in times that we might have overall patterns of risk for people, such as droughts in some parts of the world, or in climates with seasonal changes when we might have hurricanes or winter blizzards or deep freezes. Meteorologists also use more sophisticated instruments to predict the weather anywhere from one day to a season (more generally, of course) in advance. Those instruments include weather satellites, which collect information on the varying patterns of weather (particularly the formation of storm centers and other visibly observable weather phenomena) that meteorologists use in their predictions. Meteorologists also use weather maps to record and track the data from all of the other instruments, and then analyze the data as shown on the map to predict the weather to come over the next few days or so.