Precipitati on Chapter 7 t a t i p i c e r P 7 r e t p a h C Precipitation When we think of precipitation we think of Fourth level Fifth level Rain Drizzle Edit Master text styles Snow Second level Flurries Third level Sleet Freezing Rain Hail Forms of water that fall from the sky Beneficial ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Formation of Cloud Droplets Condensation Nuclei Particles in the air Dust Edit Master text styles Dirt Second level Salt Third level Fourth level Fifth level Water vapor molecules adhere to condensation nuclei and will cool condense form cloud droplets ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Formation of Cloud Droplets process of air Cloud droplet growth is aided by the The droplets are held in the air by slow rising currents Edit Master text styles Second level Third level If the cloud drop finds it s way out of the cloud it will before reaching the ground If condensation was the only method for growing precipitation sized particles it would take to Fourth level Fifth level these are called create a raindrop ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Growth of a Raindrop The growth of a cloud droplet is extremely slow and simple growth by condensation is not what forms raindrops Edit Master text styles Second level There are two processes that explain the formation of Third level Fourth level Fifth level rain drops 1 Collision and Coalescence Process cloud 2 Bergeron Process cloud process process ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Precipitation Process Collision and Coalescence Process Collisions between cloud drops of different sizes grow Edit Master text styles rain drops in Second level clouds Third level Drops must be of and have different speeds ATM SC 1050 Introduction to Meteorology Large drops overtake small Fourth level drops Fifth level often capturing them Forming Rain Drops Larger drops fall faster than smaller ones s the Sometime large drop will break apart t a t i p i c e r P 7 r e t p a h C Precipitation Process Collision and Coalescence Process Factors that determine rainfall production range of droplet sizes Edit Master text styles cloud thickness Second level updrafts in the cloud Third level electrical charges Fourth level Fifth level Cumulonimbus clouds have lots of moisture drops of all sizes strong updrafts and highly charged particles and are producers of precipitation ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Precipitation Process Bergeron Process This is an ice crystal Edit Master text styles Second level Third level cloud process that produces precipitation Clouds with both ice and water are called Some water droplets are existing at temperatures below freezing they are Fourth level Fifth level ATM SC 1050 Introduction to Meteorology Precipitation Process Bergeron Process t a t i p i c e r P 7 r e t p a h C In a mixed cloud many droplets surround each ice crystal Edit Master text styles Second level Some water molecules are moving enough to avoid Third level freezing to the ice crystals others are not The ice crystals will in a sense the super cooled water droplets and them over to their side of the sky Hence droplets become ATM SC 1050 Introduction to Meteorology and Fourth level Fifth level t a t i p i c e r P 7 r e t p a h C Precipitation Process Ice crystals grow rapidly eventually falling toward the ground Fourth level Fifth level Edit Master text styles Accretion Ice crystals can with supercooled drops Second level and cause instant freezing to form snow pellets Third level Snow pellets ice crystals will continue to fall and collide with each other Eventually they ll into tiny pieces The falling ice crystals and tiny pieces will collide and to other ice crystals ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Precipitation Process Average Snowfall in North America Edit Master text styles Second level Third level Fourth level Fifth level ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Precipitation Types Virga Rain that leaves a cloud base but before reaching the ground Not technically precipitation since nothing reaches the Edit Master text styles ground Second level look below a cloud Third level Fourth level Fifth level ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Precipitation Types Fallstreaks particles ice crystals that fall from cirrus clouds and in the air below them Fourth level Fifth level Edit Master text styles Second level Third level ATM SC 1050 Introduction to Meteorology t a t i p i c e r P 7 r e t p a h C Precipitation Types Edit Master text styles Second level Third level Snow All precipitation or most of it starts off as snow It either or stays as an ice Fourth level Fifth level The size and structure of the ice crystals is a function of the temperature at which they form When air temperatures are the moisture content is very small This results in very light snow made up of six sided ice crystals When conditions are the ice crystals join 1 together into larger clumps Snow Liquid Ratio for snowflakes for snowflakes ATM SC 1050 Introduction to Meteorology This Photo by t a t i p i c e r P 7 r e t p a h C Precipitation Types Sleet A tiny ice pellet Starts with a falling from the cloud Edit Master text styles Second level It falls into a layer with above temps Third level The snow into a raindrop Raindrop falls into a deep freezing layer at the surface and into an ice pellet ATM SC 1050 Introduction to Meteorology This Photo by Fourth level Fifth level t a t i p i c e r P 7 r e t p a h C Precipitation Types Freezing Rain Rain that instantly freezes upon a sub freezing surface Start with a snowflake falling from the cloud falling into a Edit Master text styles Second level Third level layer with above freezing temps Snow melts into a Drop falls into a freezing layer near the surface Fourth level Fifth level and doesn t have time to re freeze Drop hits an object that is below freezing spreads out and freezes ATM SC 1050 Introduction to Meteorology This Photo by t a t i p i c …