Explain what relative humidity must be like if clouds begin to form in the sky?

Lesson Objectives

Hash out the difference betwixt weather condition and climate.
Draw the relationship between air temperature and humidity, including the concept of dew point.
List the basics of the different cloud types and what they bespeak nigh current and future weather.
Explain how the different types of precipitation form.

Vocabulary

cloud
dew point
relative humidity

Introduction

If someone across country asks you what the weather is like today, you need to consider several factors. Air temperature, humidity, current of air speed, the amount and types of clouds, and precipitation are all part of a thorough weather report. In this affiliate, yous will learn well-nigh many of these features in more detail.

What is Atmospheric condition and Climate?

Atmospheric condition is what is going on in the atmosphere at a particular place at a item fourth dimension. Weather can change apace. A location'south conditions depends on:

air temperature
air pressure
fog
humidity
cloud cover
precipitation
wind speed and management

All of these are directly related to the amount of free energy that is in the arrangement and where that energy is. The ultimate source of this energy is the dominicus.

Climate is the average of a region'south weather over time. The climate for a item place is steady, and changes only very slowly. Climate is determined by many factors, including the angle of the Sun, the likelihood of cloud cover, and the air pressure. All of these factors are related to the amount of energy that is found at that place over time.

Humidity

Humidity is the amount of water vapor in the air in a particular spot. We usually use the term to mean relative humidity, the pct of water vapor a certain book of air is holding relative to the maximum amount it can contain. If the humidity today is lxxx%, it means that the air contains 80% of the full amount of water information technology can hold at that temperature. What will happen if the humidity increases to more than 100%? The excess h2o condenses and forms precipitation.

Since warm air tin can hold more water vapor than cool air, raising or lowering temperature can change air'south relative humidity (Effigy below). The temperature at which air becomes saturated with water is called the air'due south dew point. This term makes sense, considering h2o condenses from the air as dew, if the air cools downwards overnight and reaches 100% humidity.

This diagram shows the amount of water air can hold at different temperatures. The temperatures are given in degrees Celsius.

Clouds

Clouds have a big influence on conditions:

by preventing solar radiation from reaching the ground.
by absorbing warmth that is re-emitted from the footing.
every bit the source of atmospheric precipitation.

When there are no clouds, there is less insulation. Equally a result, cloudless days can be extremely hot, and cloudless nights can exist very cold. For this reason, cloudy days tend to accept a lower range of temperatures than clear days.

Clouds grade when air reaches its dew betoken. This tin happen in two ways: (1) Air temperature stays the same merely humidity increases. This is common in locations that are warm and humid. (2) Humidity can remain the same, but temperature decreases. When the air cools plenty to reach 100% humidity, h2o droplets form. Air cools when it comes into contact with a common cold surface or when information technology rises.

Rising air creates clouds when information technology has been warmed at or near the ground level and then is pushed upward over a mount or mount range or is thrust over a mass of cold, dense air.

Water vapor is not visible unless it condenses to go a cloud. H2o vapor condenses effectually a nucleus, such equally grit, fume, or a salt crystal. This forms a tiny liquid droplet. Billions of these water aerosol together make a cloud.

Clouds are classified in several ways. The well-nigh common classification used today divides clouds into four split up deject groups, which are determined by their altitude (Effigy beneath).

The four cloud types and where they are found in the temper.

Loftier Clouds

Loftier clouds (Effigy below) form from ice crystals where the air is extremely cold and tin can agree little water vapor. Cirrus, cirrostratus, and cirrocumulus are all names of high clouds.

(a) Cirrus clouds are thin wisps of water ice crystals found at high altitudes. (b) Cirrostratus clouds are sparse white sheets of ice crystals that are sometimes invisible unless backlit by the Sun or Moon.

Cirrocumulus clouds are pocket-sized, white puffs that ripple across the heaven, often in rows. Cirrus clouds may point that a storm is coming.

Centre Clouds

Middle clouds, including altocumulus and altostratus clouds, may be made of water aerosol, ice crystals or both, depending on the air temperatures (Effigy below).

Altocumulus clouds are white to puffy stripes rolling across the heaven. They may precede a thunderstorm.

Thick and broad altostratus clouds are gray or bluish-grey. They frequently cover the unabridged heaven and usually mean a large tempest, begetting a lot of atmospheric precipitation, is coming.

Low Clouds

Low clouds (Effigy below) are nearly all water droplets. Stratus, stratocumulus and nimbostratus clouds are common depression clouds.

(a) Stratus clouds are grey sheets that cover the entire heaven and may produce a steady drizzle. Stratus clouds with the Alps in the distance. (b) Stratocumulus clouds are rows of large, low puffs that may be white or gray. These clouds rarely bring atmospheric precipitation.

Nimbostratus clouds are thick and dark. They bring steady pelting or snowfall.

Vertical Clouds

Clouds with the prefix 'cumulo-' (Figure below) grow vertically instead of horizontally and have their bases at low altitude and their tops at loftier or centre altitude. Clouds grow vertically when strong air currents are rising upward.

(a) Cumulus clouds resemble white or light gray cotton and accept towering tops and may produce light showers. (b) A cumulonimbus cloud grows when vertical air currents are strong as in a thunderstorm. This ane is lit up by lightning.

An online guide to deject evolution and different cloud types from the University of Illinois is found here: http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/cld/home.rxml.

Fog

Fog (Figure below) is a cloud located at or near the ground . When humid air virtually the ground cools below its dew indicate, fog is formed. The several types of fog that each form in a different style.

Radiations fog forms at night when skies are clear and the relative humidity is loftier. As the ground cools, the lesser layer of air cools beneath its dew indicate. Tule fog is an extreme course of radiation fog found in some regions.
San Francisco, California, is famous for its summertime advection fog. Warm, moist Pacific Ocean air blows over the common cold California electric current and cools beneath its dew betoken. Sea breezes bring the fog onshore.
Steam fog appears in autumn when cool air moves over a warm lake. Water evaporates from the lake surface and condenses as information technology cools, appearing like steam.
Warm humid air travels up a hillside and cools beneath its dew point to create upslope fog

(a) Tule fog in the Primal Valley of California. (b) Advection fog in San Francisco. (c) Steam fog over a lake. (d) Upslope fog in Teresópolis city, Rio de Janeiro State, Brazil.

KQED: Science on the SPOT: The Science of Fog

Fog levels are declining along the California coast as climate warms. The change in fog may have big ecological changes for the state. Learn more at: http://science.kqed.org/quest/video/science-on-the-spot-science-of-fog/.

Precipitation

Atmospheric precipitation (Figure below) is an extremely important part of weather. Some precipitation forms in place .

(a) Dew forms when moist air cools beneath its dew point on a cold surface, such every bit a flower. (b) Frost is dew that forms when the air temperature is below freezing; hoar frost.

The most common precipitation comes from clouds. Pelting or snow droplets grow as they ride air currents in a deject and collect other aerosol (Figure beneath). They autumn when they go heavy plenty to escape from the rising air currents that hold them upwardly in the cloud. I million cloud aerosol volition combine to make simply one rain drop ! If temperatures are cold, the droplet volition hit the ground equally a snowflake.

(a) Rain falls from clouds when the temperature is fairly warm. (b) Snow tempest in Boston, Massachusetts.

Other less common types of precipitation are sleet (Effigy below).

(a) Sleet is rain that becomes ice as information technology hits a layer of freezing air near the footing. (b) If a frigid raindrop freezes on the frigid ground, it forms coat. (c) Hail forms in cumulonimbus clouds with strong updrafts. An ice particle travels until it finally becomes too heavy and it drops. This big hail stone is nearly 6 cm (two.5 inches) in bore.

An online guide from the University of Illinois to different types of precipitation is seen here: http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/cld/prcp/home.rxml.

Lesson Summary

Different air temperatures create convection cells.
Air ascension in a convection cell may cool enough to reach its dew indicate and course clouds or precipitation if the humidity is loftier enough.
Clouds or fog may form if warmer air meets a colder basis surface. Air temperature and humidity likewise determine what sorts of clouds and atmospheric precipitation form.
Unlike factors play a role in creating pleasant or uncomfortable weather, such every bit when it might exist warm and dry or hot and humid.

Review Questions

What factors need to be included in a thorough weather report?
If Phoenix, Arizona, experiences a cool, wet day in June (when the weather is commonly hot and dry), does that mean the region'southward climate is changing?
What happens when a batch of air reaches its dew point? What is the temperature?
What outcome do clouds take on atmospheric condition?
Y'all are continuing in a location that is clear in the morning, but in the afternoon there are thunderstorms. There is no wind during the day, then the thunderstorms build direct in a higher place you. Describe how this happens.
What are the iv unlike deject groups and how are they classified?
How does sleet course? How does glaze class?
What circumstances must exist present for enormous balls of hail to grow and then fall to the ground?

Points to Consider

When thinking about the atmospheric condition, what factors do you consider important?
How do air temperature, humidity, and pressure differences create dissimilar weather?
Think about the types of weather described in this lesson. Imagine types of weather condition that y'all take not experienced, expect at photos, and inquire friends and relatives who've lived in other places what their weather is like.

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Source: https://courses.lumenlearning.com/sanjac-earthscience/chapter/weather-and-atmospheric-water/