Sun in afternoon In mid latitude is overhead which causes heat which leads to convective activity

Conduction: heat is physically transferred by molecules by contact , ground gets heated by sun rays and air very close to the ground gets heated by conduction,

Convection in this process hot fluid is bodily xfered to the colder part of the fluid more than 70 % earth is covered by water hence convection is important

Temperature at fl160 is -22°c

if you descend in troposphere temperature will increase 2°c per 1000 feet( lapse rate as per isa)

fl160 to

fl90

descend is 7000 feet

Temperature gained is 2×7=14°c

add 14°c to -22°c

answer is -8°c

Radiation fog is caused by radiation of the earth’s heat at night, and the subsequent conductive cooling of the air in contact with the ground to below dew point.

If there is a light wind, then fog will form, in calm conditions the result will be the formation of dew. The fog is not usually more than a few hundred feet thick.

Conditions necessary for radiation fog to form.

Clear sky – to increase the rate of terrestrial radiation.

High relative humidity – so that a little cooling will be enough to cause saturation and condensation.

Light wind – of 2 – 8 kts to mix the layers of air causing turbulence so that droplets will be kept in suspension and so that warmer air from above can be brought into contact with the cold ground to thicken the fog.

The average rate of cooling within a static atmosphere would be 0.65°C/100m (1.98°C per 1000ft.)

However, in reality the environmental lapse rate varies significantly from day to day and season to season, especially in the lower layers of the atmosphere

A layer of atmosphere where the temperature remains same with increase in height is called isothermal

example, just above the tropopause.

Time in Paris is 1800 UTC

LOCAL TIME IS 0400 PM

As per diurnal variation of temperature

From 15:00 LMT onwards, the temperature falls continuously until a little after sunrise. The lowest temperature occurs at about sunrise plus 30 minutes. (TMIN)

it is past 1500 let by 1 hr

so temperature will fall slightly below

3°c

1. Inversion is also called negative lapse rate

Where the temperature increases with an increase in height, then we have what is called an inversion. We have already seen that at night we can expect an inversion above the surface, but this can occur in many different ways.

1. Inversion is also called negative lapse rate

Where the temperature increases with an increase in height, then we have what is called an inversion. We have already seen that at night we can expect an inversion above the surface, but this can occur in many different ways.

As per diurnal variation of temperature

From 15:00 LMT onwards, the temperature falls continuously until a little after sunrise. The lowest temperature occurs at about sunrise plus 30 minutes. (TMIN)

Solar radiation heats the ground and then Atmosphere is heated from the ground  that is the reason why temperature reduces with height in troposphere

Negative lapse rate in stratosphere:

Inversion means increase in temperature with height

it occurs due to uv ray absorption by ozone

Radiation, on a night of clear skies, will also result in a temperature inversion above the surface. This is called a Radiation Inversion.

wind and cloud cover will cause T max to be reduced and T min to be increased.

WIND: wind will cause turbulent mixing of the warm air at the surface with cold air above, reducing T max.

CLOUD: the solar radiation is reflected back by the cloud tops

1. Inversion is also called negative lapse rate

Where the temperature increases with an increase in height, then we have what is called an inversion. We have already seen that at night we can expect an inversion above the surface, but this can occur in many different ways.

wind and cloud cover will cause T max to be reduced and T min to be increased.

WIND: wind will cause turbulent mixing of the warm air at the surface with cold air above, reducing T max.

CLOUD: the solar radiation is reflected back by the cloud tops

Lapse rate in isa -2°C per 1000 feet of climb

And temperature is 15 ° C at msl

climbing 10000 feet we reduce -2°C every 1000 feet

hence temperature lost is -20°C

now add this to 15° C( temperature at msl)

result is -5°C

add 10°c.

We get 5°c

The ICAO ISA is defined as follows:-

a MSL temperature of 15°C

a MSL pressure of 1013.25 hPa

a MSL density of 1225 g/m3

a lapse rate of 0.65°C/100m (1.98° C /1000 ft) up to 11 km (36,090 ft)

a constant temperature of -56.5°C from 11 km (36,090ft) to 20 km (65,617 ft)

an increase of temperature 0.1°C/100m (0.3°C /1000 ft), from 20 km (65,617ft) to 32 km (104,987 ft)