16.1 WEATHER AND ATMOSPHERIC WATER

Learning Targets 1.Discuss the difference between weather and climate 2.Describe the relationship between air temperature and humidity, including the concept of dew point 3.List the basics of the different cloud types and what they indicate about current and future weather 4.Explain how the different types of precipitation form

Weather vs. Climate 1.Weather: condition of the atmosphere at any given time 2.Climate: long term averages of weather

Weather 1.Weather depends on: a)Air temperature b)Air pressure c)Dew point d)Humidity e)Cloud cover f)Precipitation g)Wind speed and direction 2.All are directly related to amount of energy in system

Humidity 1.Humidity - Amount of water vapor in air a)Usually ~3% 2.Relative humidity - % of water vapor certain volume of air is holding relative to maximum amount it can contain

Humidity 1.Precipitation occurs when relative humidity is over 100% 2.Dew point = 100% humidity 3.Two ways to reach dew point a)Lower temperature b)Increase water content

Clouds 1.Clouds form when air reaches its dew point 2.Serve several roles a)Preventing solar radiation from reaching ground b)Absorbing warmth that is re-emitted from ground c)Source of precipitation 3.Classified based on height a)Strato (low), Alto (middle), Cirro (high) 4.Classified based on shape a)Cumulus, stratus, cirrus

Cloud Height 1.Cirro – High 2.Alto – Middle 3.Strato - Low

Cloud Shapes 1.Cumulus: puffy cotton ball 2.Stratus: even layers 3.Cirrus: wispy tufts

Fog 1.Radiation fog a)Cold ground cools air beyond its dew point b)Most common 2.Steam fog a)Forms over lakes and ponds at night because water is warm and air is cool

Precipitation 1.Dew a)Warm air contacting cold surface 2.Rain/Snow a)Drops/flakes too heavy to be held up by air currents b)Melt or remain frozen depending on temperature 3.Hail a)Extremely strong currents push water back up into the cloud several times