Lesson 20: Elements of Weather

• Weather - temperature, air pressure, humidity, wind, and clouds
• Temperature - a substance's hotness/coldness
• Thermometer - used to measure temperature in degrees Celsius or Fahrenheit.
• Stevenson Screen - a white wooden box with louvers edges
• To guarantee that the ambient air temp matches the thermometer, it must be shaded from the sunlight and subjected to proper ventilation
• Air pressure - the level of force applied by the air in a given air mass.
• Air pressure is measured using a barometer.
• Humidity - the amount of water vapor in the atmosphere

  • indicates the likelihood of precipitation, snow, dew or fog
• Absolute humidity - packet of air denoted by the amount of water and vapor present
• Relative humidity - obtained by comparing the actual mass of vapor in the air
• Wind - created when there is a change in pressure or temperature between two points on the Earth's surface
• Anemometer - an instrument that can be used to measure the speed of the wind
• Clouds -noticeable array of water droplets and/or ice crystals held in the atmosphere that can take on a wide range of sizes and shapes
• 4 Major types of clouds:

  1 . Cirrus

  2. Nimbus

  3. Cumulus

  4. Stratus
• Altostratus - form ahead of storms

  Altocumulus - humid morning can form into thunderstorms
• Nimbostratus - low-level stratus clouds with continuous precipitation
• Cumulonimbus - towering vertical cloud, often associated with severe weather such as hail, lightning, tornadoes, and hurricanes.
• Cirrocumulus - small white puffy clouds
• Cirrostratus - thin sheet of cirrus clouds covering most of sky