Allah (swt) says:
And those on the left hand – who will be those on the Left Hand? In fierce hot wind and boiling water. And shadow of black smoke, [that shadow] neither cool, nor [even] good“. (56:41-44)

This aayah includes all of the things that people avail themselves of in this world when it is too hot; these three things are: water, air and shade. But the aayah states that these three things will be of no help whatsoever to the people of Hell. The air of Hell is al-Sumoom, which is an intensely hot wind; its water is al-Hameem, boiling water; its shade is al-Yahmoom, which is a part of the smoke of Hell. (at-Takhweef min an-Naar, p.85)

Just as this aayah emphasizes the horrifying position of those on the Left Hand, who are the people of Hell, another aayah emphasizes the horror of Hell itself. Allah (swt) says:

But he whose balance [of good deeds] will be [found] light, will have his home in a [bottomless] pit. And what will explain to you what this is? [It is] a Fire blazing fiercely!” (101:8-11)

The shade referred to in the aayah “and the shadow of black smoke” (56:43) is the shade cast by the smoke of Hell. Shade usually makes one feel cool and comfortable, and people love to feel it, but this shade [in Hell] will neither be cool nor pleasant; it is the shadow of black smoke.

The Qur’an tells us that this shade is the smoke of Hell which rises above the Fire:
Depart you to a shadow [of smoke ascending] in three columns, [which yields] no shade of coolness and is of no use against the Fierce Blaze”. Indeed! It [Hell] throws about sparks [huge] as forts, as if there were [a string of] yellow camels [marching swiftly].” (77:30-33)

This aayah states that the smoke that rises from Hell is so great that it is divided into three columns. It gives shade, but it is not cooling and it offers no protection from the Raging Fire. The sparks that fly from this Fire are like huge castles, and they are likened to yellow or black camels.

Allah (swt) explained how strong this Fire is, and how it affects the tormented:
“Soon I will cast him into Hellfire. And what will explain to you exactly what Hellfire is? Naught does it permit to endure, and naught does it leave alone! Darkening and changing the color of man!” (74:26-29)

The Fire consumes all, destroying everything and leaving nothing untouched. It burns skin, reaching to the bone, melting the contents of the stomach and exposing what is innermost.

The Prophet (saw) told us: “Fire as we know it is one-seventieth part of the Fire of Hell.” Someone said, “O Messenger of Allah (saw), it is enough as it is!” He said, “It [the fire of Hell] is as if sixty nine equal portions were added to the fire as we know it.” (al-Bukhaari)

This Fire never dies down, no matter how much time passes:
So taste you [the results of your evil actions]; no increase shall We give you, except in torment“. (78:30)
“…whenever it abates, We shall increase for them the fierceness of the Fire“. (17:97)

The disbelievers will not taste the luxury of respite, and the torment will not be lessened for them no matter how long it lasts:
Their torment shall not be lightened nor shall they be helped“. (2:86)

The Fire is rekindled every day as is stated in the hadith reported by Muslim from ‘Amr ibn ‘Absah (ra) who said:
“The Prophet (saw) said, “Pray salaat as-subh (the early morning prayer) then stop praying when the sun is rising until it is fully up, for it rises between the horns of Shaytaan and the disbelievers prostrate to the sun at that time. Then pray, for the prayer is witnessed (by the angels) until the shadow becomes the length of a lance. Then cease prayer, for at that time Hell is heated up. Then when the shadow moves forward, pray..

al-Bukhaari and Muslim report from Abu Hurayrah (ra) that the Prophet said, “When it becomes very hot, wait until it cools down to pray, because the intense heat is a breeze from Hell“.

The Fire of Hell will be further refueled on the Day of Resurrection when it receives its inhabitants:

And when Hellfire shall be kindled to a fierce blaze, and when Paradise shall be brought near“. (81:12-13)